Bazel: Fix relative go to definition in external repositories (#103)

Summary:
The resolve root was calculated incorrectly for relative load statements in external repositories. Instead of removing the file's path relative to the external repository, it only kept this part. For example if the current file is `$(bazel info output_base)/external/foo/bar/BUILD`, it would compute the resolve root as `bar/BUILD`, whereas it needs to be `$(bazel info output_base)/external/foo`.

Pull Request resolved: #103

Reviewed By: stepancheg

Differential Revision: D52887182

Pulled By: ndmitchell

fbshipit-source-id: 3025ae7be81a85976f2e250c104de7163db6a6a5

starlark_bin/bin/bazel.rs

@@ -423,10 +423,8 @@ impl BazelContext {
                 // system information to check if we're in a known remote repository, and what the
                 // root is. Fall back to the `workspace_root` otherwise.
                 ("", LspUrl::File(current_file)) => {
-                    if let Some((_, remote_repository_root)) =
-                        self.get_repository_for_path(current_file)
-                    {
-                        Some(Cow::Borrowed(remote_repository_root))
+                    if let Some((repository_name, _)) = self.get_repository_for_path(current_file) {
+                        self.get_repository_path(&repository_name).map(Cow::Owned)
                     } else {
                         workspace_root.map(Cow::Borrowed)
                     }