This commit adds a confessions feature that allows users to mark a
"confessional" channel and also to post anonymously to it. The changes
that this comprises of are as follows:
- New discord "slash" commands for both marking a confessional and
posting to it
- a bunch of stuff in the discord module to register and deregister
"slash" commands
- New event type to track marked confessionals
- confession module that processes new confession channel links
and also posts confessions to corresponding confessionals
Not included in this commit:
- a way to cleanup obsolete or reconfigured confession channel links
- access control for the confessional slash commands
Signed-off-by: Ava Affine <ava@sunnypup.io>
