Adjust the layout of the blame information in blob page as soon as user triggers it

Proposal

When the user triggers the blame page, it awaits the server response to adjust the layout. This leads to a slower perceived performance.

If we do it in two steps:

1. Trigger the layout adjustment as soon as the user triggers the Blame button
2. Populate the left column with data when the server responds

Then the changes to the page happen incrementally.

If we add a css-transition to extend the size progressively it might even be completely sequential.