add roles to admin panel

db/migrate/20220721133408_create_roles.rb

@@ -0,0 +1,11 @@
+class CreateRoles < ActiveRecord::Migration[7.0]
+  def change
+    create_table :roles do |t|
+      t.string :name
+
+      t.timestamps
+    end
+
+    add_index(:roles, :name, unique: true)
+  end
+end

db/migrate/20220721133421_create_join_table_user_role.rb

@@ -0,0 +1,8 @@
+class CreateJoinTableUserRole < ActiveRecord::Migration[7.0]
+  def change
+    create_join_table(:users, :roles, unique: true) do |t|
+      t.index(%i[user_id role_id])
+      t.index(%i[role_id user_id])
+    end
+  end
+end

db/schema.rb

@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema[7.0].define(version: 2022_07_21_132939) do
+ActiveRecord::Schema[7.0].define(version: 2022_07_21_133421) do
   # These are extensions that must be enabled in order to support this database
   enable_extension "plpgsql"
 
@@ -118,6 +118,20 @@ ActiveRecord::Schema[7.0].define(version: 2022_07_21_132939) do
     t.index ["user_id"], name: "index_review_requests_on_user_id"
   end
 
+  create_table "roles", force: :cascade do |t|
+    t.string "name"
+    t.datetime "created_at", null: false
+    t.datetime "updated_at", null: false
+    t.index ["name"], name: "index_roles_on_name", unique: true
+  end
+
+  create_table "roles_users", id: false, force: :cascade do |t|
+    t.bigint "user_id", null: false
+    t.bigint "role_id", null: false
+    t.index ["role_id", "user_id"], name: "index_roles_users_on_role_id_and_user_id"
+    t.index ["user_id", "role_id"], name: "index_roles_users_on_user_id_and_role_id"
+  end
+
   create_table "subjects", force: :cascade do |t|
     t.string "name"
     t.bigint "category_id", null: false