avoid using alias in generators

Ruby's alias produces public methods, causing a spurious Thor task
to be created.  For example, this is the reason MigrationGenerator
currently has two tasks:

    > ActiveRecord::Generators::MigrationGenerator.all_tasks.keys
    => ["singular_name", "create_migration_file"]

singular_name was meant to be an attribute, not a task.  Because it's
public, it gets called as a task every time the generator is invoked.

The fix is to ensure all generator methods have the correct
visibility.
Fix migrations with enable_extension

When using ActiveRecord::Base.table_name_prefix and/or
table_name_suffix, extension names got the same treatment as table names
when running migrations. This led to migrations that tried to call, for
example, enable_extension("prefix_hstore") on the connection.
Hash#deep_*_keys(!) recurse into nested arrays.

Following methods now recursively transform nested arrays, too.

* Hash#deep_transform_keys
* Hash#deep_transform_keys!
* Hash#deep_stringify_keys
* Hash#deep_stringify_keys!
* Hash#deep_symbolize_keys
* Hash#deep_symbolize_keys!
Check authentication scheme in Basic auth

`authenticate_with_http_basic` and its families should check the authentication
schema is "Basic".

Different schema, such as OAuth2 Bearer should be rejected by basic auth, but
it was passing as the test shows.

This fixes #10257.
Run login_procedure only when the auth_scheme is valid
Fixed `columns_for_distinct` of postgresql adapter
Added partial days support to `DateTime`'s `advance` method.

You can now add partial days (e.g. 2.5.days) to `DateTime` with the advance method.
This was acheived by mimicing the `advance` implementation in `Time`.
Fixed changelog
Fix serialized field returning serialized data after update_column
Added documentation for the :param option for resourceful routing
Fixes Issue #13466.

Changed the call to a scope block to be evaluated with instance_eval.
The result is that ScopeRegistry can use the actual class instead of base_class when
caching scopes so queries made by classes with a common ancestor won't leak scopes.
Swallow bundler exceptions when running tests

Let's avoid useless output when testing stuff related to Bundler.
Allow custom asset host to be passed in asset_url
Improve documentation for asset_url

Updated CHANGELOG.md with entry about :host in asset_url
Fixed duplicate subscribers in ActiveSupport::Subscriber

ActiveSupport::Subscriber no longer creates multiple subscribers when
you redefine a method.
Remove unnecessary include for integration tests.
:scissors:
Fixed a problem where `sum`, `size`, `average`, `minimum` and `maximum` used
with a grouping was not returning a Hash.
Add missing requires for require 'action_dispatch/routing'
Only path requirements are relevant to optimized urls

The bit of URL generation that is optimized is the generation of
the path so things like :host, :port, etc. are irrelevant.