The xorm `Sync2` has already been deprecated in favor of `Sync`,
so let's do the same inside the Gitea codebase.
Command used to replace everything:
```sh
for i in $(ag Sync2 --files-with-matches); do vim $i -c ':%sno/Sync2/Sync/g' -c ':wq'; done
```
Change all license headers to comply with REUSE specification.
Fix#16132
Co-authored-by: flynnnnnnnnnn <flynnnnnnnnnn@github>
Co-authored-by: John Olheiser <john.olheiser@gmail.com>
* make repo as "pending transfer" if on transfer start doer has no right to create repo in new destination
* if new pending transfer ocured, create UI & Mail notifications