Add keybindings with numpad keys for Zoom commands and handle multiple keybindings per command

[AlexandraBuzila]

What it does

• Add keybindings with the + and - keys from the numpad for the Zoom In and Zoom Out commands, in the electron app (Fixes [electron] Zoom commands don't work with the numpad keys #11239)
• Display all available keybindings for a command in the Keyboard Shortcuts dialog and handle multiple keybindings in the keymaps.json (Fixes Only one keybinding is visible per command in Keybindings dialog #11240)

How to test

Zoom In and Out should work with the + and - keys from the numpad.

To test the handling of multiple keybindings for one command:

1. Open the Keyboard Shortcuts editor and keymaps.json
2. Search for Zoom In command in the editor -> two entries should show
3. Modify one of the entries and change the keybinding in the editor -> two new entries should be visible in keymaps.json, one for the new keybinding and one that disables the default one
4. Save keymaps.json to update the UI
5. Modify the second (default) entry for the Zoom In command in the editor -> two new entries should be visible in keymaps.json, one for the new keybinding and one that disables the default one
6. Save keymaps.json to update the UI
7. Modify the second (default) entry again in the editor -> one entry should update in the keymaps.json (the one that was added at step 5)
8. Save keymaps.json to update the UI
9. Reset one of the Zoom In commands in the editor -> both commands should return to their default values and the command should be removed completely from keymaps.json

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]

@AlexandraBuzila do you mind taking a look at the failing tests?

[AlexandraBuzila]

I rebased the branch and updated the failing test.

[vince-fugnitto]

I confirmed that the changes work well for me 👍

There is a difference between our behavior and that of vscode but I prefer ours. Basically I noticed in VS Code that if you modify each entry for a command that has multiple keybindings vscode will only have one active at a time.

I did notice some issues when performing updates, and doing a revert (where the whole file is deleted) so I opened #11399 which should fix it.

[msujew]

The changes look good to me as well 👍

• The view displays all keybindings when multiple keybindings exist
• Changing these keybindings is correctly applied (after saving the keymaps.json)
• Reseting a keybinding resets all of the keybindings for the same command

I originally though I've noticed an issue when swapping two keybindings for a command (one disappears), but vscode behaves in the same way, so at least it is consistent. I also believe there's no better way dealing with this.

[JonasHelming]

@vince-fugnitto : Are you fin with merging this?

[vince-fugnitto]

LGTM 👍