Add public blocks to /about/blocks (#11298)

* Add automatic blocklist display in /about/blocks

Inspired by https://github.com/Gargron/mastodon.social-misc

* Add admin option to set who can see instance blocks

* Normalize locales files

* Rename “Sandbox” to “Silence” for consistency

* Disable /about/blocks when in whitelist mode

* Optionally display rationale for domain blocks

* Only display domain blocks that have user-facing limitations, and order them

* Redesign table of blocked domains to better handle long domain names and rationales

* Change domain blocks ordering now that rationales aren't displayed right away

* Only show explanation for block severities actually in use

* Reword instance block explanations and add disclaimer for public fetch mode

app/models/domain_block.rb

@@ -25,6 +25,7 @@ class DomainBlock < ApplicationRecord
   delegate :count, to: :accounts, prefix: true
 
   scope :matches_domain, ->(value) { where(arel_table[:domain].matches("%#{value}%")) }
+  scope :with_user_facing_limitations, -> { where(severity: [:silence, :suspend]).or(where(reject_media: true)) }
 
   class << self
     def suspend?(domain)