[Feature] add `app.delete()` method

[deven298]

Description

This PR enables deleting sources from the db.

from embedchain import App

app = App()

source_id = app.add("https://www.forbes.com/profile/elon-musk")

app.delete(source_id=source_id)

Type of change

Please delete options that are not relevant.

• [ ] Bug fix (non-breaking change which fixes an issue)
• [x] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
• [ ] Refactor (does not change functionality, e.g. code style improvements, linting)
• [x] Documentation update

How Has This Been Tested?

• [ ] Unit Test
• [x] Test Script

Checklist:

• [x] My code follows the style guidelines of this project
• [x] I have performed a self-review of my own code
• [x] I have commented my code, particularly in hard-to-understand areas
• [x] I have made corresponding changes to the documentation
• [x] My changes generate no new warnings
• [x] I have added tests that prove my fix is effective or that my feature works
• [x] New and existing unit tests pass locally with my changes
• [x] Any dependent changes have been merged and published in downstream modules
• [x] I have checked my code and corrected any misspellings

Maintainer Checklist

• [x] closes #1175
• [x] Made sure Checks passed

[codecov[bot]]

Codecov Report

Attention: 5 lines in your changes are missing coverage. Please review.

Comparison is base (7444f59) 55.56% compared to head (51a7de4) 57.10%. Report is 3 commits behind head on main.

Files	Patch %	Lines
embedchain/embedchain.py	20.00%	4 Missing :warning:
embedchain/vectordb/base.py	50.00%	1 Missing :warning:

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1187      +/-   ##
==========================================
+ Coverage   55.56%   57.10%   +1.54%     
==========================================
  Files         143      143              
  Lines        5712     5719       +7     
==========================================
+ Hits         3174     3266      +92     
+ Misses       2538     2453      -85     

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