fix(sortable): unsubscribe item capture when component is destroyed

[Arooba-git]

Hello 👋 As part of our project, we are using Facebook's new Memlab tool to detect memory leaks in SPA applications. While running the tool and analyzing the code of ngx-bootstrap, we saw that your project does a very good job of ensuring that all async operations are cancelled when the component unmounts. However, as per Memlab execution results, we found a dangling subscription that was causing the memory to leak (screenshots below).

[before]
Hence we added the fix by unsubscribing the subscription and you can see the heap size and # of leaks reducing noticeably:

As per the contribution guidelines, we ran the unit test cases; NX successfully ran the target tests for 24 projects. You can analyze this and other potential leak sources, if you like, by running Memlab with a scenario file covering the maximum # of use cases. Following is a sample of the scenario file we used (it needs to be a .js file but attaching here in .txt form): ngx-test-scenario-memlab.txt

Note that some other reported leaks (in Memlab) originated from Storybook, hence were ignored.

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 42.85714% with 4 lines in your changes missing coverage. Please review.

Project coverage is 76.59%. Comparing base (e77c928) to head (b98712f). Report is 1 commits behind head on development.

Files with missing lines	Patch %	Lines
src/sortable/sortable.component.ts	42.85%	4 Missing :warning:

Additional details and impacted files

@@               Coverage Diff               @@
##           development    #6546      +/-   ##
===============================================
- Coverage        76.60%   76.59%   -0.01%     
===============================================
  Files              317      317              
  Lines            10748    10754       +6     
  Branches          2866     2866              
===============================================
+ Hits              8233     8237       +4     
- Misses            2514     2516       +2     
  Partials             1        1              

Files with missing lines	Coverage Δ
src/sortable/sortable.component.ts	8.24% <42.85%> (+1.65%)	:arrow_up:

... and 5 files with indirect coverage changes

---

Continue to review full report in Codecov by Sentry.

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[cypress[bot]]

35 failed tests on run #3851 ↗︎

35

803

14

0

0

Details:

Merge 0375b49d6ae355317216020e3642123e7579f227 into 663c70e688dfbc0215683c76cc25...
Project: ngx-bootstrap	Commit: 4329b38ec4 ℹ️
Status: Failed	Duration: 36:47 💡
Started: Jan 27, 2023 9:22 PM	Ended: Jan 27, 2023 9:59 PM

  datepicker/locales_spec.ts • 2 failed tests • full

View Output Video

Test
Datepicker demo testing suite: Locales > Change Locale Datepicker > when user chose locale es-pr for "Datepicker", container shown in appropriate language		Screenshot
Datepicker demo testing suite: Locales > Change Locale DateRangepicker > when user chose locale es-pr for "Daterangepicker", container shown in this language		Screenshot

  typeahead_page_spec.ts • 1 failed test • full

View Output Video

Test
Typeahead demo page testing suite > On blur > clicking anywhere outside auto-fills "Option on blur" with the first option from the matches list		Screenshot

  modals_service_page_spec.ts • 13 failed tests • full

View Output Video

Test
Modals demo page testing suite: Service examples > Component modals with interceptor > when user clicks on "Close" button, triggers the interceptor and doesn't close the modal		Screenshot
Modals demo page testing suite: Service examples > Component modals with interceptor > when user clicks on "Yes" button, closes the modal		Screenshot
Modals demo page testing suite: Service examples > Component modals with interceptor > when user clicks on "No" button, doesn't close the modal		Screenshot
Modals demo page testing suite: Service examples > Nested modals > when user clicks on the button "Open second modal" then the second modal with title "Second modal" is opened, "Close self" is present		Screenshot
Modals demo page testing suite: Service examples > Events > when user closes modal by click on the cross then should be messages "onHide event has been fired" and "onHidden event has been fired"		Screenshot
Modals demo page testing suite: Service examples > Events > when user closes modal by pressing ESC button then modal is closed and should be messages "onHide event has been fired" and "onHidden event has been fired"		Screenshot
Modals demo page testing suite: Service examples > Confirm Window > when user clicks on "Open modal" button then modal is opened, it contains two buttons: "Yes" and "No"		Screenshot
Modals demo page testing suite: Service examples > Custom css class > when user clicks on the cross button then the modal is closed		Screenshot
Modals demo page testing suite: Service examples > Animation option > when user clicks on the cross button then the modal is closed		Screenshot
Modals demo page testing suite: Service examples > Esc closing option > when user clicks on "Open modal" button then modal is opened. when user closes modal by click ESC button then modal stays opened		Screenshot
The first 10 failed tests are shown, see all 13 tests in Cypress Cloud.

  popover_page_spec.ts • 1 failed test • full

View Output Video

Test
Popover demo page testing suite > Component level styling > when user clicks on "I have component level styling", then popover-container appear above the button		Screenshot

  tabs_page_spec.ts • 1 failed test • full

View Output Video

Test
Tabs demo page spec > Dynamic tabs > when user clicks on close icon near tab, then this tab removed		Screenshot

The first 5 failed specs are shown, see all 13 specs in Cypress Cloud.

_{This comment has been generated by cypress-bot as a result of this project's GitHub integration settings.}

[Arooba-git]

bump @valorkin

[Arooba-git]

@lexasq Does this PR need any update on my part? :)

[lexasq]

@Arooba-git thanks for your contribution, this PR definitely caught my eye to have a better look. No actions needed on your part, we appreciate your help to make this lib better!