Fix open diff on sg bug
Created by: abeatrix
Currently we are combining the baseUrl and repoName with a hardcorded /
in between before we construct the final URL to open diff on Sourcegraph in Code host; however, if the baseUrl has already had a dash at the end, the hardcoded /
will also be added which would break the URL.
To resolve this, I've added the new URL
method that we use in the OpenOnSourcegraph to construct the URL to make sure the last dash will be removed from the baseURL before we construct the final URL.
This should fix https://github.com/sourcegraph/sourcegraph/issues/28035