Fix up from #12210: Excel without UIA enabled: again allow typing and editing in cells

[michaelDCurran]

Link to issue number:

Fixes #12303

Summary of the issue:

After merging of pr #12210 editing cells in Excel without UIA enabled became im possible as NVDA did not report / track focus had ented the Cell Edit control.
This was due to the EXCEL6 window accidentally being marked as having a good UIA implementation. This was testing code left over from the early implementation of #12210.

Description of how this pull request fixes the issue:

Remove EXCEL6 from the good UIA windows list.
Also ensure that MSAA focus events on this window are ignored when using Excel with UIA enabled, as Excel will fire its own UIA focus event on an edit control within the active cell.

Testing strategy:

Testing with all combinations of NvDA's use Microsoft Excel with UI Automation setting, and Excel's allow directly editing in a cell setting (4 different variations possible):
In an Excel spreadsheet:

• Started typing into a cell. Ensured that NVDA was announcing the typed characterrs, and that it announced focus moving into the edit control.
• Pressed f2 on a cell, ensured that NVDA announced focus on the edit control, that characters were announced when typed, and that moving the cursor with left and right arrows would speak the characters in the edit control.

This was successful for all 4 variations of the two settings.

Known issues with pull request:

None known.

Change log entries:

None needed.

Code Review Checklist:

• Pull Request description is up to date.
• Unit tests.
• System (end to end) tests.
• Manual tests.
• User Documentation.
• Change log entry.
• Context sensitive help for GUI changes.

[seanbudd]

Tested using the suggested method in the PR, and confirmed that the original issue is fixed. LGTM