Compare two different branches from two different repositories using UI and API.

Description

Compare branches from two different repositories using the API and UI.

To enable us to use the API and UI to compare 2 branches from two different repositories.

Proposal

We were trying to compare two different branches from two different repos but this doesn't seem to be possible at the moment. It would be extremely useful for us to do this using the API and also the UI.

Use cases

For our development team to be able to compare two different branches from two different repositories for code comparison and fault finding.

Feature checklist

Make sure these are completed before closing the issue, with a link to the relevant commit.

Feature checklist

Make sure these are completed before closing the issue, with a link to the relevant commit.