Use ascii-only labels for Electron menus

[colin-grant-work]

What it does

Fixes #10672 by avoiding adding non-ascii arrow characters to 'accelerator' labels in Electron menus.

How to test

1. On MacOS
2. Run the Electron application
3. Open the Selection menu.
4. See this (with the arrows that Electron uses):

5. Run the Browser application
6. Open the selection menu
7. See this (with arrow characters):

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

[vince-fugnitto]

I confirmed that the changes work well 👍

before:

after:

I also confirmed there are no regressions, and it also works in the browser.