Add config/tokens.yml template
Remove secret_token.rb
Load secret_key_base from tokens.yml, fallback to config.secret_key_base
Replace config.secret_key_base with secrets.secret_key_base in test
Add test for custom tokens stored in config/tokens.yml
Rename tokens.yml to secrets.yml
Perf: save ~9% of object allocations on heavy requests.

The per-thread registry is keyed on the class name, and each request for
the class name returns a new string. This is in the hot path for a lot
of Active Record behavior, so we easily accumulate thousands of repeated
strings.

To fix, we simply cache the key when the class is first extended with
the module.

TODO: Eliminate this module. The per-thread instance concept is common,
but this technique confuses and obfuscates.
Correct comment in databases/postgresql.yml
Add a bunch of Relation -> Array delegate methods to the whitelist. This won't last - aim to switch back to a blacklist for mutator methods.
Merge pull request #13303 from dvsuresh/typo_postgresqlyml

Correct comment in databases/postgresql.yml [ci skip]
form_tag with parameters fixed [ ci skip ]
Merge pull request #13305 from psahni/form_tag_with_parameters

form_tag with parameters fixed [ci skip]
extract PG range tests from datatype_test.rb into range_test.rb
refactor, reuse assertions in range_test.rb.
Fix mysql to support duplicated column names

This will fix the [broken
test](https://github.com/rails/rails/commit/4a2650836680f51490e999c3c8441a2f9adff96e)
 `test_with_limiting_with_custom_select`.

The query's result was built in a hash with column name as key, if the
result have a duplicated column name the last value was
overriding the first one.
Merge pull request #13306 from kassio/master

Fix mysql to support duplicated column names
argument prefix warning removed

* interpreted as a argument prefix
Merge pull request #13309 from arunagw/warning-fix-argumnet

argument prefix warning removed
Add comment about secret_key_base in secrets.yml
Merge pull request #13298 from rails/secret_tokens

Create config/secrets.yml file for store of tokens