Handle Windows paths in git: URI construction (#6)

Alternative formulations that don't use gitApi.toGitUri are possible:

    vscode.Uri.from({ …, path: "/" + path, … })

    vscode.Uri.from({ …, path: vscode.Uri.file(path).path, … })

    vscode.Uri.file(path).with({ scheme: …, query: … })

The first alternative works, but mixes forward- and back-slashes (the
incoming path has backslashes).

The last two alternatives should be equivalent and give the same result
as the version in this commit. All of them convert the directory
separators to forward slashes, so the final URI looks like (e.g.)

    git:///c%3A/Users/me/Documents/…?…

Note: The path property in the encoded query component seems like it
must use backslashes on Windows. toGitUri uses fsPath for the encoded
path property. Also, I got a different failure opening the vscode.diff
link when I tried using slashes in the query's path property.

toGitUrl: https://github.com/microsoft/vscode/blob/65a6a2f783dbc87fb3b1408c6a9b3e8d455a60a2/extensions/git/src/uri.ts#L32

Author: ChrisJohnsen

Diff for: src/extension.ts

@@ -500,7 +500,7 @@ function buildHoverMessage(info: CommitInfo) {
 }
 
 function gitUri(ref: Sha, path: string) {
-  return vscode.Uri.from({ scheme: "git", path, query: JSON.stringify({ ref, path }) });
+  return gitApi.toGitUri(vscode.Uri.file(path), ref)
 }
 
 function getRepo(uri: vscode.Uri) {