[API Feature Request] Custom form for extention/command preference properties

[yoavbls]

Describe the feature and the current behavior/state.
Today only static forms are supported for extension/command user preferences.
It would be great to have the ability to use custom components (mostly Form component) in user preferences
to get rich forms like many built-in extensions have. e.g:

Will this change the current api? How?
It doesn't break any API, It just can be added as a new type for preferences section in extension manifest
like textfield / password / checkbox / dropdown

Who will benefit with this feature?

• Developers who want to create dynamic autosuggestions for their extension preferences, login buttons for oAuth or similar auth types, etc.
• Users may get simpler options to fill preferences, login buttons instead of API token input.

Any Other info.
My specific use case is preferences for Google Tasks extension that I develop,
Now I perform the oAuth2 login flow + task list selection in the main Command component
instead of the preferences form because it isn't possible.

#178 will solve the login flow issue but not the dynamic task list selection.