Disabled MenuItem roles on macOS.

[kittaakos]

Motivation

The MenuItem#role support is broken in Theia. This PR disables the role and falls back to the default, command-based execution on click.

Change description

Disabled the role support on macOS.

Other information

This issue must be macOS-specific and should be verified by a macOS user.

Reviewer checklist

• PR addresses a single concern.
• The PR has no duplicates (please search among the Pull Requests before creating one)
• PR title and description are properly filled.
• Docs have been added / updated (for bug fixes / features)

[kittaakos]

@ubidefeo, please verify if you have some time. Thank you!

[ubidefeo]

I tested this build.
The first Undo operation is ignored.

If I add 3 new lines anywhere, the first time I select Edit > Undo nothing happens.
Subsequent clicks undo the edit

[kittaakos]

Thank you for the review, @ubidefeo.

This PR is intended to fix Menu item "Edit > Select All" only select 10 lines of code #969.

However, I can confirm that Edit > Undo does not work in IDE2. Undo does not work with the latest 2.0.0-rc7, and it does not work in Theia either.

[ubidefeo]

@kittaakos
now I see why I tested "Undo": it's mentioned in the Theia issue linked above.
I did not make it up to be related to the one I reported (#969 )

[ubidefeo]

LGTM