Add customizable user roles (#18641)

* Add customizable user roles

* Various fixes and improvements

* Add migration for old settings and fix tootctl role management

spec/policies/status_policy_spec.rb

@@ -6,7 +6,7 @@ require 'pundit/rspec'
 RSpec.describe StatusPolicy, type: :model do
   subject { described_class }
 
-  let(:admin) { Fabricate(:user, admin: true) }
+  let(:admin) { Fabricate(:user, role: UserRole.find_by(name: 'Admin')) }
   let(:alice) { Fabricate(:account, username: 'alice') }
   let(:bob) { Fabricate(:account, username: 'bob') }
   let(:status) { Fabricate(:status, account: alice) }