Add Content assist to the Find/Replace overlay in RegEx Mode

[Wittmaxi]

Missing feature which exists in the Dialog but not (yet) in the overlay

[github-actions]

Test Results

 1 815 files  ±0   1 815 suites  ±0   1h 33m 31s ⏱️ - 6m 52s
 7 682 tests ±0   7 454 ✅ ±0  228 💤 ±0  0 ❌ ±0 
24 207 runs  ±0  23 458 ✅ ±0  749 💤 ±0  0 ❌ ±0 

Results for commit 46aacfa. ± Comparison against base commit fd8ce3e.

♻️ This comment has been updated with latest results.

[HeikoKlare]

In general, this looks good and is a great enhancement for regex search in the find/replace overlay. There is just one functional problem: the enablement is only updated when activating/reactivating the regex option, but this only affects the replace bar if it is open at that point in time. Thus, when opening the replace bar, content assist will always be enabled, because it's enablement is not initialized.

In the following screenshot, I have just opened the overlay and then opened the replace bar. Even though the regex option is disabled, content assist is activated for the replace input field:

[HeikoKlare]

Duplicate forceFocus() should not be necessary in the open() method.