Enable more frozen string in lib/**/*.rb

Enables frozen for the following:

* lib/*.rb
* lib/banzai/**/*.rb
* lib/bitbucket/**/*.rb
* lib/constraints/**/*.rb
* lib/container_registry/**/*.rb
* lib/declarative_policy/**/*.rb

Partially addresses #47424.

lib/version_check.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require "base64"
 
 # This class is used to build image URL to