Add option to specify hard-coded TS types to a particular instance of the Monaco editor created using the module from T2991: Extract Monaco editor as a separate module.

This is to enable autocomplete and typechecking when someone is for example editing a TS snippet that will be used in a known environment.

There should also be an option to not provide any types.

Some discussion is likely necessary to make this happen in an elegant manner, hence this is 2 points. 1 point from that is to compensate for the design part.