Optional filter text autocomplete support in chevron pop up

[elsazac]

Refs : https://github.com/eclipse-platform/eclipse.platform.ui/issues/194

This PR address one of the feature suggestion in https://github.com/eclipse-platform/eclipse.platform.ui/issues/194.

This PR includes an autocomplete feature in the chevron popup filter, making it easier to navigate when too many editors are opened in the workbench. As the user types, matching editor names are suggested in the filter text area and the remaining part is auto-filled, improving speed and efficiency in locating editors.

This enhancement is implemented as an optional feature for the filter text in chevron pop up ie, users can enable or disable the autocomplete option based on their preference. A checkbox option to enable and disable the autocomplete behaviour is given in the Eclipse -> Settings -> General page. The feature is controlled through a new preference flag, ENABLE_AUTOCOMPLETE_IN_CHEVRON, stored under org.eclipse.ui.workbench. Users can enable or disable autocomplete in the Workbench Preferences, and when disabled, the chevron shows the normal standard filtering behaviour.

Key changes:

1. Introduced a new optional autocomplete behaviour in the chevron popup to provide suggestions and auto completion.
2. Normal text filtering is still available.
3. Added a checkbox in Preference page to let users enable or disable the autocomplete option depending upon their preference.
4. By default the option is disabled, but if the feature is to be enabled it can be done via Eclipse -> Settings -> General -> Enable autocomplete option in chevron popup

https://github.com/user-attachments/assets/5c9183b7-ee77-474b-8cad-b8d5e97dde3e

[github-actions[bot]]

Test Results

 3 018 files  ±0   3 018 suites  ±0   2h 7m 1s ⏱️ - 7m 6s  8 234 tests ±0   7 985 ✅ ±0  249 💤 ±0  0 ❌ ±0  23 622 runs  ±0  22 828 ✅ ±0  794 💤 ±0  0 ❌ ±0 

Results for commit 3f43f463. ± Comparison against base commit 7a24db1a.

:recycle: This comment has been updated with latest results.

[elsazac]

@merks Would you be able to take a look at this?