Added GroupPinnedStatuses

• Added:
- GroupPinnedStatuses
- controllers for timeline, creation, deletion
- redux actions, reducers for creation, deletion
- timeline fetching in timelines action
- options to pin, unpin in status options popover for group admin

app/validators/group_pinned_status_validator.rb

@@ -0,0 +1,10 @@
+# frozen_string_literal: true
+
+class GroupPinnedStatusValidator < ActiveModel::Validator
+  def validate(groupPin)
+    groupPin.errors.add(:base, I18n.t('statuses.group_pin_errors.reblog')) if groupPin.status.reblog?
+    groupPin.errors.add(:base, I18n.t('statuses.pin_errors.ungrouped')) unless groupPin.status.group_id
+    groupPin.errors.add(:base, I18n.t('statuses.pin_errors.notGroupStatus')) if groupPin.status.group_id != groupPin.group.id
+    groupPin.errors.add(:base, I18n.t('statuses.group_pin_errors.limit')) if groupPin.group.group_pinned_statuses.count >= 4
+  end
+end