Avoid compiling regexs in AR::Base.respond_to?

Caches the patterns of ActiveRecord::DynamicMatchers in a class instance
variable.
Merge pull request #11971 from freerunningtechnologies/dynamic_respond_to

Performance regression in AR::Base.respond_to?
Add a note about edge guides in the feedback section[ci skip]
Merge pull request #11991 from prathamesh-sonpatki/note-edge-guides

Add a note about edge guides in the feedback section [ci skip]
remove unused instance variable
Merge pull request #11994 from rajcybage/fix_instance

remove not used instance variable
Fix typo in file path, should include extension.
Merge pull request #11996 from semaperepelitsa/master

Docs: fix typo in file path, should include extension. [ci skip]