Implement favoriting of projects

db/migrate/20200529081537_create_favorite_projects.rb

@@ -0,0 +1,12 @@
+class CreateFavoriteProjects < ActiveRecord::Migration[6.0]
+  def change
+    create_table :favorite_projects, id: false do |t|
+      t.integer :id, null: false
+      t.integer :user_id, null: false
+      t.string :title
+
+      t.timestamps
+    end
+    add_index :favorite_projects, :id, unique: true
+  end
+end