Add member events to webhooks table

This is just adding the column, actual implementation will come after

changelogs/unreleased/group-member-webhook-column.yml

+---
+title: Add member_events column to web_hooks table
+merge_request: 49273
+author:
+type: added

db/migrate/20201204205814_add_member_events_to_web_hooks.rb

+# frozen_string_literal: true
+
+class AddMemberEventsToWebHooks < ActiveRecord::Migration[6.0]
+  DOWNTIME = false
+
+  def change
+    add_column :web_hooks, :member_events, :boolean, null: false, default: false
+  end
+end

db/schema_migrations/20201204205814

+8178b8a9acf7d2d8990bb6f7d984eb9e3b77d45cb2a8b54b56500ef6f93772ad
\ No newline at end of file

db/structure.sql

@@ -17713,7 +17713,8 @@ CREATE TABLE web_hooks (
     encrypted_url_iv character varying,
     deployment_events boolean DEFAULT false NOT NULL,
     releases_events boolean DEFAULT false NOT NULL,
-    feature_flag_events boolean DEFAULT false NOT NULL
+    feature_flag_events boolean DEFAULT false NOT NULL,
+    member_events boolean DEFAULT false NOT NULL
 );
 
 CREATE SEQUENCE web_hooks_id_seq