Change domain blocks to automatically support subdomains (#11138)

* Change domain blocks to automatically support subdomains

If a more authoritative domain is blocked (example.com), then the
same block will be applied to a subdomain (foo.example.com)

* Match subdomains of existing accounts when blocking/unblocking domains

* Improve code style

app/controllers/admin/domain_blocks_controller.rb

@@ -13,7 +13,7 @@ module Admin
       authorize :domain_block, :create?
 
       @domain_block = DomainBlock.new(resource_params)
-      existing_domain_block = resource_params[:domain].present? ? DomainBlock.find_by(domain: resource_params[:domain]) : nil
+      existing_domain_block = resource_params[:domain].present? ? DomainBlock.rule_for(resource_params[:domain]) : nil
 
       if existing_domain_block.present? && !@domain_block.stricter_than?(existing_domain_block)
         @domain_block.save

app/controllers/admin/instances_controller.rb

@@ -18,7 +18,7 @@ module Admin
       @blocks_count    = Block.where(target_account: Account.where(domain: params[:id])).count
       @available       = DeliveryFailureTracker.available?(Account.select(:shared_inbox_url).where(domain: params[:id]).first&.shared_inbox_url)
       @media_storage   = MediaAttachment.where(account: Account.where(domain: params[:id])).sum(:file_file_size)
-      @domain_block    = DomainBlock.find_by(domain: params[:id])
+      @domain_block    = DomainBlock.rule_for(params[:id])
     end
 
     private

app/controllers/media_proxy_controller.rb

@@ -39,6 +39,6 @@ class MediaProxyController < ApplicationController
   end
 
   def reject_media?
-    DomainBlock.find_by(domain: @media_attachment.account.domain)&.reject_media?
+    DomainBlock.reject_media?(@media_attachment.account.domain)
   end
 end