apiTypes.ts should be self contained

[rchiodo]

Testing #19103

It takes a bunch of hunting down types to use the apiTypes.ts file. It would be nice if all the types needed were defined in this one spot.

Examples:

vscode-python/src/client/apiTypes.ts

Line 6 in c46c819

import { IDataViewerDataProvider, IJupyterUriProvider } from './jupyter/types';

[karrtikr]

Yes, we plan to publish an npm package for the types.

[eleanorjboyd]

moving to the environments extension API so no longer applicable