Keyboard shortcut cannot be changed and overlaps with a native RemNote one

Namely, `ctrl+shift+:` is "Zoom Out of Rem & Open in Other Pane" by default. Given that I can change the native shortcuts, I assume the inability to change Cloze Hint's is the fault of either the plugin, or all plugins.

Reproduce the conflict in RemNote using the `ctrl+shift+:` shortcut and inspect how Cloze Hints registers it. Determine whether the plugin or the plugin system owns shortcut configurability; done means the shortcut can be changed or no longer overlaps with RemNote's native command.

Written by the indexing model from the issue text.