Make CacheableRegistry strictly typed

This changes the typed mode for this module from
'true' to 'strict', which requires annotations
for methods and variables.

app/lib/registries/cacheable_registry.rb

@@ -1,19 +1,23 @@
-# typed: true
+# typed: strict
 module Registries
   module CacheableRegistry
+    extend T::Sig
     include Kernel
 
+    sig {returns(TrueClass)}
     def can_refresh_cache?
       true
     end
 
+    sig {returns(T::Boolean)}
     def refresh_cache
       Rails.cache.write(cache_key, cacheable_data)
     rescue GdsApi::HTTPServerError, GdsApi::HTTPBadGateway
       report_error
       false
     end
 
+    sig {returns(T::Hash)}
     def fetch_from_cache
       Rails.cache.fetch(cache_key) do
         cacheable_data
@@ -23,14 +27,17 @@ def fetch_from_cache
       {}
     end
 
+    sig {void}
     def cacheable_data
       raise NotImplementedError, "Please supply a cacheable_data method"
     end
 
+    sig {void}
     def cache_key
       raise NotImplementedError, "Please supply a cache_key method"
     end
 
+    sig {void}
     def report_error
       raise NotImplementedError, "Please supply a report_error method"
     end