Updates all copyright notices to include "Ghostty contributors" to
reflect the fact that Mitchell is not the sole copyright owner.
Also adds "Ghostty contributors" to the author section in the manpages,
linking https://github.com/ghostty-org/ghostty/graphs/contributors for
proper credit.
This reverts commit 14134d61fb4b1bbf4ce80bb9b3ed849908bf9344, reversing
changes made to 6a876ef8ec3e2aeb3d15df0dfb0e07677e49ff03.
This causes translation failures, this should be reintroduced when the
CI check passes.
