Fix loading of string arrays in postgres
Fix freeze applying to cloned objects

Previously, freezing a cloned ActiveRecord object froze the original
too. By cloning `@attributes` before freezing, we prevent cloned objects
(which in Ruby share state of ivars) from being effected by `#freeze`.

Resolves issue #4936, which has further information on this issue, as
well as steps to reproduce.

* Add a test case for `#freeze` not causing `cloned.frozen?` to be true.
* Clone @attributes before freezing in `ActiveRecord::Core`, then
  reassign the cloned, frozen hash to the frozen model's `@attributes`
  ivar.

/cc @steveklabnik
Adding a local thread registry to store local caches.
adding a test for root path in the app
Merge pull request #10250 from wangjohn/local_cache_registry

Adding a local thread registry to store local caches.
add :nodoc: mark to *Registry classes [ci skip]
Add nodoc to LocalCacheRegistry

[ci skip]
Merge pull request #10252 from epiclabs/nodoc_registries

add :nodoc: mark to *Registry classes [ci skip]
activerecord-deprecated_finders 1.0.0 has a bug with has_many :through
associations
Refactored the storage of a temporary version of the local cache into
its own method.
Merge pull request #10254 from wangjohn/refactoring_local_cache

Refactored the storage of a temporary version of the local cache.
The increment and decrement commands in the local cache are exactly the
same, so their logic is being refactored.
Merge pull request #10255 from wangjohn/increment_or_decrement_refactoring_in_local_cache

Refactoring increment and decrement in local cache
Fix subject-verb agreement in error msg (and other grammar stuff)
Use secure source for rubygems in engine tests
Merge pull request #10259 from prathamesh-sonpatki/secure-engine-tests

Use secure source for rubygems in engine tests
Merge pull request #10258 from thenickcox/pending_migrations_plural

Fix subject-verb agreement in error msg (and other grammar stuff)
Support transactions in Migrator.run
Avoid leak into controller's action_methods
Merge pull request #10262 from printercu/patch-3

Avoid leak into controller's action_methods