Code Quality: Fixed a number of focus related issues in Omnibar

[yaira2]

Resolved / Related Issues

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• For Feature: Added support for opening the breadcrumb dropdown via keyboard navigation #16092
• Fixed "Entering text in Command mode, switching to Edit path mode, and then back to Command mode doesn't clear the original text"
• Fixed "Pressing tab in Command mode closes flyout but doesn't switch to the next control"
• Fixed "Switching to Path mode from Command mode isn't selecting the text"
• Moved the logic for resetting the selected mode on LostFocus from the app into the control

Steps used to test these changes

Stability is a top priority for Files and all changes are required to go through testing before being merged into the repo. Please include a list of steps that you used to test this PR.

Fixed Command Palette text when switching between modes

1. Entered text in Command mode
2. Switched to Edit path mode
3. Switched back to Command mode
4. Confirmed the text was correctly cleared

Moved the logic for resetting the selected mode on LostFocus from the app into the control

1. Switched to Edit path mode
2. Removed focus by clicking the file area
3. Confirmed the Omnibar switched to Breadcrumb mode
4. Switched to Command mode and repeated steps 2 and 3

Pressing tab in Command mode closes flyout but doesn't switch to the next control

1. Focused on path box
2. Pressed tab
3. Confirmed the breadcrumb bar is selected
4. Switched to Command mode
5. Confirmed pressing tab selects the mode button

Switching to Path mode from Command mode isn't selecting the text

1. Switched to Command mode
2. Switched to Edit path mode
3. Confirmed the text was selected