Clear cache after setting Template::Types delegate

details_cache_key already references Template::Types.symbols and view
resolvers cache based on default_formats and other values. This
previously wasn't an issue because no views had been looked up before
this was set. Now that we are building a regex from the values of
Template::Types.symbols we need to clear cache after changing this
setting.

actionmailer/lib/action_mailer.rb

@@ -67,4 +67,5 @@ def self.eager_load!
 ActiveSupport.on_load(:action_view) do
   ActionView::Base.default_formats ||= Mime::SET.symbols
   ActionView::Template::Types.delegate_to Mime
+  ActionView::LookupContext::DetailsKey.clear
 end

actionpack/lib/action_dispatch.rb

@@ -116,4 +116,5 @@ module Session
 ActiveSupport.on_load(:action_view) do
   ActionView::Base.default_formats ||= Mime::SET.symbols
   ActionView::Template::Types.delegate_to Mime
+  ActionView::LookupContext::DetailsKey.clear
 end

railties/test/application/per_request_digest_cache_test.rb

@@ -62,7 +62,7 @@ def index
   end
 
   test "template digests are cleared before a request" do
-    assert_called(ActionView::LookupContext::DetailsKey, :clear) do
+    assert_called(ActionView::LookupContext::DetailsKey, :clear, times: 3) do
       get "/customers"
       assert_equal 200, last_response.status
     end