The logic for replacing conflicting shortcuts removes all keybindings from the other shortcut

[krassowski]

Description

If user wants to add a new keybinding for command A, say "Ctrl + J", but command B already uses "Ctrl + J" they will be shown an information about the conflict:

There are two problems:

• if "Ctrl + J" is the default shortcut, it will not be overwritten when clicking "Overwrite"
• if command B had multiple keybindings assigned, say "Ctrl + J" and "Ctrl +Shift + J" (and both are non-default), both will be removed

This is ok-ish:

jupyterlab/packages/shortcuts-extension/src/components/ShortcutInput.tsx

Lines 136 to 143 in f00eef9

	handleOverwrite = async () => {
	this.props
	.deleteShortcut(
	this.state.takenByObject.takenBy,
	this.state.takenByObject.takenByKey
	)
	.then(this.handleUpdate());
	};

This is bad, see that shortcutId is not being used:

jupyterlab/packages/shortcuts-extension/src/components/ShortcutUI.tsx

Lines 392 to 399 in f00eef9

	/** Delete shortcut for command, refresh state */
	deleteShortcut = async (
	shortcutObject: ShortcutObject,
	shortcutId: string
	): Promise<void> => {
	await this.handleUpdate(shortcutObject, ['']);
	await this._refreshShortcutList();
	};

Related to #15937.

Expected behavior

Only the relevant keybinding is removed, and it is removed reliably regardless if it is default or not

Context

• JupyterLab version: 4.1.5