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 e466f9d10e145a3ed750f0c86cfcafad5f141ea8)
(cherry picked from commit e33e95931b0d91c41433db68ddb19a8724b8ed80)
(cherry picked from commit 5f528f0a25)
(cherry picked from commit 65146bfbcd1102a8e182ac6967804659fea9651f)