Improve accessibility of the dropdown menu.

[jansiegel]

Context

This PR:

• Adds aria-haspopup to the TH elements containing the dropdownMenu buttons.
• Excludes the dropdown menu from reacting to Cmd/Ctrl+A, previously introduced by Improve keyboard shortcuts navigation throughout the context and dropdown menus #10519.

[skip changelog]

How has this been tested?

Modified the existing test case for Cmd/Ctrl+A to match the current requirements.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature or improvement (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Additional language file or change to the existing one (translations)

Related issue(s):

1. handsontable/dev-handsontable#1465

Affected project(s):

• handsontable
• @handsontable/angular
• @handsontable/react
• @handsontable/vue
• @handsontable/vue3

Checklist:

• I have reviewed the guidelines about Contributing to Handsontable and I confirm that my code follows the code style of this project.
• I have signed the Contributor License Agreement
• My change requires a change to the documentation.

[budnix]

I'm able to trigger the default Cmd+A action on a submenu

[budnix]

The Cmd+A keyboard shortcut should not work in the dropdown list of the Filter by condition component

[magierg]

Cmd/Ctrl+A works as expected on macOS & Windows in 14.0.0: https://jsfiddle.net/ezs4hgmn/