fix: incremental loading for actions

[johnny243]

• actions are displayed as soon as they are resolved
• loading spinner is shown per extension

[moughxyz]

As mentioned in the SNJS PR, loading should be a client side concern. Easy solution would be to add a loadingState record in ActionsMenu:

private readonly loadingState: Record<UuidString, Boolean> = {}

And then use/modify that as needed.

[johnny243]

I've removed the hidden property from the extension class: standardnotes/snjs#87

[arielsvg]

Please upgrade SNJS and make sure type info is still correct