Config descriptions for custom MRF policies

Closes #2222

See merge request pleroma/pleroma!3128

- revert UserAllowPolicy description
- MRF descriptions order

Resolve "Wrong user link in Report email"

Closes #2260

See merge request pleroma/pleroma!3121

Fix title on load of Pleroma HTML, fixes #2281

Closes #2281

See merge request pleroma/pleroma!3125

Escaping in xml templates

Closes #2291

See merge request pleroma/pleroma!3126

Remove release_env

See merge request pleroma/pleroma!3124

While taking a final look at instance.gen before releasing I noticed
that the release_env task outputs messages in broken english. Upon
further inspection it seems to have even more severe issues which, in
my opinion, warrant it's at least temporary removal:
- We do not explain what it actually does, anywhere. Neither the task
 docs nor instance.gen, nor installation instructions.
- It does not respect FHS on OTP releases (uses /opt/pleroma/config even
 though we store the config in /etc/pleroma/config.exs).
- It doesn't work on OTP releases, which is the main reason it exists.
Neither systemd nor openrc service files for OTP include it.
- It is not mentioned in install guides other than the ones for Debian
and OTP releases.

Expiring mutes for users and activities

Closes #1817

See merge request !2971

don't run  Stats GenServer updates in tests

See merge request !2976

Add TagPolicy as default MRF

See merge request !2834

Add ejabberd auth document

See merge request !3074

Add a federation_status endpoint showing unreachable instances

See merge request !3086

View a remote server's timeline

See merge request !2713

Always return voters_count in polls

See merge request !3120

Merge branch 'develop' of git.pleroma.social:pleroma/pleroma into alexgleason/pleroma-restrict-domain

Hide chats from muted users

Closes #2230

See merge request !3116

favicon: Use images/pleroma_logo_vector_bg_32.png from pleroma.social

Closes #2270

See merge request !3115

ConversationView: add current user to conversations, according to Mastodon behaviour, fix last_status.account being not filled

Closes #2217

See merge request !3089

Closes: #2270