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)
(cherry picked from commit 24dc0a5191)
(cherry picked from commit e255eea2b4)
(cherry picked from commit 0c4f5afa7a)
