Merge branch 'feat/mrf-noemptypolicy' into 'develop'

MRF NoEmptyPolicy: Deny posts from local users if there is no content or only mentions.

See merge request pleroma/pleroma!3309

diff --combined CHANGELOG.md
index 378e0466ec39c4e823f7205618f964ab902ce4b5,d4acbc9a587ccadd7a9a9fa53ef5f9e235c24446..e89836b7a0ba75e490b4effdf78df0ab380661bd
--- 1/CHANGELOG.md
--- 2/CHANGELOG.md
+++ b/CHANGELOG.md
@@@ -19,8 -19,6 +19,8 @@@ The format is based on [Keep a Changelo
  - Improved Apache webserver support: updated sample configuration, MediaProxy cache invalidation verified with the included sample script
  - Improve OAuth 2.0 provider support. A missing `fqn` field was added to the response, but does not expose the user's email address.
  - Provide redirect of external posts from `/notice/:id` to their original URL
 +- Admins no longer receive notifications for reports if they are the actor making the report.
 +- Improved Mailer configuration setting descriptions for AdminFE.
  
  <details>
    <summary>API Changes</summary>
@@@ -51,6 -49,7 +51,7 @@@
  - Ability to set ActivityPub aliases for follower migration.
  - Configurable background job limits for RichMedia (link previews) and MediaProxyWarmingPolicy
  - Ability to define custom HTTP headers per each frontend
+ - MRF (`NoEmptyPolicy`): New MRF Policy which will deny empty statuses or statuses of only mentions from being created by local users
  
  <details>
    <summary>API Changes</summary>