Add ability to filter individual posts (#18945)

* Add database table for status-specific filters

* Add REST endpoints, entities and attributes

* Show status filters in /filters interface

* Perform server-side filtering for individual posts filters

* Fix filtering on context mismatch

* Refactor `toServerSideType` by moving it to its own module

* Move loupe and delete icons to their own module

* Add ability to filter individual posts from WebUI

* Replace keyword list by warnings (expired, context mismatch)

* Refactor server-side filtering code

* Add tests

app/models/form/status_filter_batch_action.rb

@@ -0,0 +1,34 @@
+# frozen_string_literal: true
+
+class Form::StatusFilterBatchAction
+  include ActiveModel::Model
+  include AccountableConcern
+  include Authorization
+
+  attr_accessor :current_account, :type,
+                :status_filter_ids, :filter_id
+
+  def save!
+    process_action!
+  end
+
+  private
+
+  def status_filters
+    filter = current_account.custom_filters.find(filter_id)
+    filter.statuses.where(id: status_filter_ids)
+  end
+
+  def process_action!
+    return if status_filter_ids.empty?
+
+    case type
+    when 'remove'
+      handle_remove!
+    end
+  end
+
+  def handle_remove!
+    status_filters.destroy_all
+  end
+end