This change moves the chat message excerpt into a new database column (string) on the chat_messages table.
As part of this change, we will now set the excerpt within the `Chat::CreateMessage` service, and update it within the `Chat::UpdateMessage` service.
Prior to this fix we were checking if user was not part of a group which allows to chat, but we were not checking if this user was part of groups who can use direct messages.
The most common thing that we do with fab! is:
fab!(:thing) { Fabricate(:thing) }
This commit adds a shorthand for this which is just simply:
fab!(:thing)
i.e. If you omit the block, then, by default, you'll get a `Fabricate`d object using the fabricator of the same name.
This change allows users to edit their chat messages based on the criteria added to Site Settings.
If the grace period conditions are met then there will be no (edited) text applied to the message.
The following site settings are added to chat:
chat editing grace period (seconds since message created)
chat editing grace period max diff for low trust levels (number of characters changed)
chat editing grace period max diff for high trust levels (number of characters changed)