Allow import/export of mutes list (#1541)

* Allow export of mutes list

* Allow importing of mutes list

* Refactor to use Settings::Exports::BaseController and DRY up exports code

app/workers/import_worker.rb

@@ -16,6 +16,8 @@ class ImportWorker
       process_blocks
     when 'following'
       process_follows
+    when 'muting'
+      process_mutes
     end
 
     @import.destroy
@@ -35,6 +37,18 @@ class ImportWorker
     CSV.new(import_contents).reject(&:blank?)
   end
 
+  def process_mutes
+    import_rows.each do |row|
+      begin
+        target_account = FollowRemoteAccountService.new.call(row.first)
+        next if target_account.nil?
+        MuteService.new.call(from_account, target_account)
+      rescue Goldfinger::Error, HTTP::Error, OpenSSL::SSL::SSLError
+        next
+      end
+    end
+  end
+
   def process_blocks
     import_rows.each do |row|
       begin