Uninstall extensions if marketplace is disabled

What does this MR do and why?

Issue: Uninstall perviously installed Extensions when ... (#460284 - closed)

This MR introduces cleanWebIdeExtensions, which uninstalls previously installed extensions if the Extensions Marketplace was disabled since the last time the user visits Web IDE.

MR acceptance checklist

Please evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.

How to set up and validate locally

Follow steps outlined here to setup Extensions Marketplace : !151352 (merged)+

Screenshots or screen recordings

Previously installed extensions are removed from IndexedDB when Extensions Marketplace was disabled since last visit:

demo.mov

The above behavior also applies when Settings Sync is enabled

settings_sync.mov

Alert message shown if cleanup fails and crossOriginExtensionHost is not enabled: