Revert API Dependency Change #49

Though #42 may have been reasonable at the time, Microsoft has not been publishing updates to its python environments extension API through npm channels. I think following the recommended method to keep this extension matched with updates to the vscode-python-environments extension by copying the api.ts file is better.

If the environments extension is updated and changes the API (it is still a "Preview"), this breaks some things that could be caught by the updated api.ts interface definitions. For example, PackageManager.refresh is now expected to return a Promise that resolves with the refreshed list of packages. I have found that this means that even with #48, the packages list will still be empty. You can see updates that fix this with a few other changes on this branch which seems to work with python-environments v1.36.0.