Add Error#full_message test; Fix typos

Introduce test on Error#full_message for attribute with underscores; Fix
some typos
Add a method full_messages_for to the Errors class
Skipping test for OpenSSL::PKCS5 JRuby
if cookie is tampered with then nil is returned [ci skip]

if the given key is not found then verifier does raise
`ActiveSupport::MessageVerifier::InvalidSignature` exception
but this exception is resuced and finally nil is returned.
Merge pull request #9916 from neerajdotname/no-exception-when-cookie-is-tampered-with

nil is retuned if cookie is tampered with [ci skip]
Fixed typo in railties/test
Merge pull request #9918 from prathamesh-sonpatki/railties-typos

Fixed typo in railties/test
Merge pull request #9864 from vipulnsward/fix_test_AR_v2

Introduce test on Error#full_message for attribute with underscores; Fix...
Merge pull request #8527 from shockone/patch-1

Add a method full_messages_for to the Errors class
Merge pull request #9874 from arunagw/skipping-test-for-openssl-pkcs5

Skipping test for OpenSSL::PKCS5 JRuby
Created a layer of abstraction for the valid type checking in schema dumper. Now, connection handles the check for valid types so that each database can handle the changes individually.