FORGEJO_* environment variables are set to the corresponding GITEA_*
variable when the cli starts. This approach is intended to minimize
the conflicts on rebase. All occurences of GITEA_* are left untouched
in the codebase and they are only changed to FORGEJO_* if exposed to
the user.
(cherry picked from commit e466f9d10e)
(cherry picked from commit e33e95931b)
(cherry picked from commit 5f528f0a25)
(cherry picked from commit 65146bfbcd)
(cherry picked from commit 393eede84a)
(cherry picked from commit df68ae9d1f)