Addressing elements not clearly visible in High Contrast mode issues

[himgoyalmicro]

Description

Addressing following issues:

1. Keyboard focus is not visible on the data cells in the table of the data grid page in High Contrast Desert mode.
2. Keyboard focus is not visible on the buttons in High Contrast Desert mode.
3. Keyboard focus faintly visible on the interactive controls of the application in High Contrast Aquatic mode.
4. Keyboard focus on the expander is not visible in Aquatic mode and faintly visible in Desert mode.
5. Selected/Focused list items in the List Box are not clearly visible in High Contrast Aquatic and Desert modes.
6. Selected "Month/Year" are not clearly visible in the High Contrast Aquatic/Desert mode.

Made the following changes:

1. Changed the KeyboardFocusBorderColor, CalendarViewItemBackgroundPointerOver and CalendarViewSelectedBackground values in High Contrast themes
2. Changed the ListBoxItemSelectedForegroundThemeBrush in the Light and Dark themes
3. Added explicit focus visual style to Button, ComboBox and DataGridCell
4. Updated the focus visual style of Expander
5. Added a Foreground property to ListBoxItem on Selected State

Customer Impact

Users relying on the High Contrast modes will be impacted if the elements are not clearly visible in High Contrast modes.

Regression

None

Testing

Local build passed, tested sample app.

Risk

NA

Microsoft Reviewers: Open in CodeFlow