This PR ensures that once opened the diff stats detail box can be scrolled independently of the diff on the compare page.
Fixes#5532
Details:
* make diff-detail-box the main container
* move file diff at the same level as diff-stats
* make diff-view options sticy again
* make diff-stats scroll if to mouch
* rm useless css info
* less: mv diff-stats to own class
* use new css class
* cleanup less file
* diff-counter: margin-right: 15px;
* make CI work
* make numbers colorful
* add sign (-/+) to numbers
* add download-button info message
* add overflow-visible css for table colum class
* right colum is always there
* add download button for default branch
* add download button for all other branchs
* resize table colum so two buttons fit in
* code indent avter rebase
* show commit divergence corect
https://github.com/go-gitea/gitea/issues/7625
* changes because of merge master into ...
* optimize if statement for protected branches
* dont downloat a deleted branch - fix error 404
6543andLunny Xiao
