apply overlay keyboard events to the top most dialog

[akosyakov]

What it does

• fix The dialog responding to the esc/enter button is unfriendly #5859 - stack of dialogs is tracked and keyboard events are applied only to the top-most dialog from the single keyboard listener for the document body
• closes Provide a safe operation for the dialog #5860 - superseded

How to test

I've pushed a temporary commit which adds a button to the open file dialog that one can open another dialog from the first. One can use it to test that on esc and enter the top-most dialog receives events. I remove this commit after the review.

Review checklist

• as an author, I have thoroughly tested my changes and carefully followed the review guidelines

Reminder for reviewers

• as a reviewer, I agree to behave in accordance with the review guidelines

[akosyakov]

@xieyuanhuata please try whether it behaves as you expect

[xieyuanhuata]

@akosyakov Great, this is the effect which I want.

[akosyakov]

@vince-fugnitto could you give it a go? if you are fine please approve and i will remove test commit

[vince-fugnitto]

I tested it using the example commit you provided and it works as intended.
I performed the following test:

1. trigger the open dialog
2. click the temporary open single text button which opens a SingleTextInputDialog`
3. press esc, only the SingleTextInputDialog is closed
4. press esc, the open dialog is closed

[akosyakov]

I've dropped the test commit, merging if CI is green and no objections.