Improve focus and navigation in Datagrid toolbar menus

[elycheea]

Original issue and fixes tracked in #3241.
These enhancements can be tested and viewed in the row height settings menu and also be checked in filter flyout.

Enhancements

• When opening the popover with enter/space, focus should go to the first item in the popover list (radio)
  • Note: There is a workaround — users have an extra tab / up/down to navigate into the popover options
• Using arrow keys to navigate radio items should not scroll the full table

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2. When you are able to correctly open the dropdown, you must press tab again - and the faint 1px blue focus state appears around settings, - then press tab a second time to enter the list before you are able to press up/down/L/R to navigate the list. Focus should be present in the first list item after pressing space/enter to activate the popover. Also as you press up/down arrows to cycle through the radio button options, the table itself moves up and down behind it.

3. When popover is open and you tab to settings, it closes. However, if popover is open and you shift+tab to Download before interacting with the popover content, the popover remains open and overlaps with the Download tooltip. I’m thinking it should close so that what happens with shift+tab is consistent with what happens with tab.
   

4. When open, the popover should dismiss when Esc is pressed

Originally posted by @kristastarr in #3117 (comment)

[elycheea]

Adding this note from @thefirstartist #2720

2. When navigating with the keyboard, users should be able to move the focus down by using the arrow down key. However, I couldn't move the focus using the arrow keys when the settings menu is open. I needed to press the tab key to shift the focus down to the menu before I could use the arrow keys to make changes.