Open changed files when opening MR in Web IDE

Problem to solve

In the old Web IDE, opening from an MR also opened all changed files. This was helpful for those looking to review the MR changes in the Web IDE or add additional changes to modified files.

Proposal

We should bring back this feature to the new Web IDE.

Opening the Web IDE from an MR should open the modified files in separate tabs.

Details

For performance reasons, we should limit this to opening the first 10 files modified in the MR.