Accessibility bug fixes (865, 950, 990, 702, 671)

[mhdahman]

Resolves:

• [865] [Keyboard Navigation-Azure Batch Explorer-Add a Pool]: Visual focus indicator is not visible for the multiple controls, while navigating using Tab key.
• [950] [Screen Readers-Azure Batch Explorer-Job>>Disable]: Visual focus indicator is not visible for the 'radio' buttons, while navigating using TAB key under the disable dialog.
• [990] [Screen Reader-Batch Explorer-Add button]: Focus moves to background while "Create a new empty container" pop-up is open.
• [702] [Keyboard Navigation - Batch Explore - Pools]: Focus order is not logical after refresh control under "Node" on "Pools" page.
• [671] [Keyboard Navigation - Batch Explore - Add a batch account]: While closing the subscription dropdown whole dialog is getting close with esc key.

Notable changes:

• keydown events handled by the select component no longer propagates
• Square buttons with primary colors now have a white focus ring
  
• Style improvements for focused and selected states of mat-radio-button
  

[codecov]

Codecov Report

Merging #2704 (34eb673) into master (c8192c1) will decrease coverage by 0.01%.
The diff coverage is 0.00%.

❗ Current head 34eb673 differs from pull request most recent head 35e32da. Consider uploading reports for the commit 35e32da to get more accurate results

@@            Coverage Diff             @@
##           master    #2704      +/-   ##
==========================================
- Coverage   65.08%   65.08%   -0.01%     
==========================================
  Files         916      916              
  Lines       26477    26478       +1     
  Branches     5237     5237              
==========================================
  Hits        17233    17233              
- Misses       9244     9245       +1     

Impacted Files	Coverage Δ
src/@batch-flask/ui/select/select.component.ts	82.80% <0.00%> (-0.30%)	⬇️

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[mhdahman]

The bl-button doesn't play nicely with the mat-menu component out of the box when used a trigger as I couldn't activate the trigger using the keyboard (at least on macOS). Mouse clicks seem fine.

mat-menu expects an actual button component to be used as a trigger, but here bl-button is a div not a button element. I had to add click and do above in order to call trigger.openMenu() programmatically.

[cRui861]

Fixes #2713