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 2cfc6519b7)
(cherry picked from commit af8864373a)
(cherry picked from commit a0550ff339)