[electron]: Listen on keyboard layout changes in electron app

[kittaakos]

What it does

From now on, the electron main sends an event to the frontend via IPC ('keyboardLayoutChanged') if the OS layout changes.

Closes #11688

How to test

I did the following (on macOS):

• build and start the electron example in debug mode,
• add a breakpoint to here and here and change your OS layout,
• you will hit both breakpoints.

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

[paul-marechal]

LGTM, good catch