This makes several changes:

* It renames the `UPDATE_SASS_PROTOCOL` environment variable used by
  the Grinder `protobuf` task to `UPDATE_SASS_SASS_REPO` to make it
  more generic and so usable by other tasks. The previous name still
  works but is considered deprecated.

* The `pkg-npm-*` grinder tasks now respects the
  `UPDATE_SASS_SASS_REPO` environment variable. This allows repos to
  ensure that the linked language repo's version of the TypeScript
  types are used when building the npm package.

* `UPDATE_SASS_SASS_REPO=false` is set for all the `pkg-npm-*` tasks
  run by this repo, so that they will use the linked language repo's
  version of the TypeScript types.

Co-authored-by: Carlos (Goodwine) <2022649+Goodwine@users.noreply.github.com>

See #2208