Extract ActiveSupport::NumberHelper methods to classes

Due to the overall complexity of each method individually as well as the
global shared private module methods, this pulls each helper into it's
own converter class inheriting from a generic `NumberBuilder` class.

* The `NumberBuilder` class contains the private methods needed for each helper
method an eliminates the need for special definition of specialized private
module methods.
* The `ActiveSupport::NumberHelper::DEFAULTS` constant has been moved
into the `NumberBuilder` class because the `NumberBuilder` is the only
class which needs access to it.
* For each of the builders, the `#convert` method is broken down to
smaller parts and extracted into private methods for clarity of purpose.
* Most of the mutation that once was necessary has now been eliminated.
* Several of the mathematical operations for percentage, delimited, and
rounded have been moved into private methods to ease readability and
clarity.
* Internationalization is still a bit crufty, and definitely could be
improved, but it is functional and a bit easier to follow.

The following helpers were extracted into their respective classes.

* `#number_to_percentage` -> `NumberToPercentageConverter`
* `#number_to_delimited` -> `NumberToDelimitedConverter`
* `#number_to_phone` -> `NumberToPhoneConverter`
* `#number_to_currency` -> `NumberToCurrencyConverter`
* `#number_to_rounded` -> `NumberToRoundedConverter`
* `#number_to_human_size` -> `NumberToHumanSizeConverter`
* `#number_to_human` -> `NumberToHumanConverter`
Use TS::Cache instead plain Hash in TimeZone.

Plain ruby Hashes are not thread safe.
Unify AS::TZ's lazy init maps.

There's no point in having 2 almost identical (@lazy_zones_map and @zones_map) lazy initialized TZ instance caches.
Remove AS::TZ.lookup(name).

The method doesn't really make much sense (find_tzinfo will succeed for any imput provided).
Add regression test for IpSpoofAttackError issue

See #10780
Move Rack::Cache after AD::Static in the stack
Fix AR#method_missing re-dispatching into overwritten attribute methods.

This was happening when a `super` call in an overwritten attribute method
was triggering a method_missing fallback, because attribute methods
haven't been generated yet.

  class Topic < ActiveRecord::Base
    def title
      # `super` would re-invoke this method if define_attribute_methods
      # hasn't been called yet resulting in double '!' appending
      super + '!'
    end
  end
Add `rake test:all`, `rake test:all:db` to guide

[ci skip]
Honor to RAILS_GROUPS env variable while loading gems with Bundler
config.assets.enabled isn't used anymore to disable Rails asset pipeline
Merge pull request #11796 from thedarkone/time-zone-thread-safety

AS::TimeZone's cache thread safety
Use genderless pronouns in API docs
EscapedString is also private API [ci skip]
Merge pull request #13123 from chancancode/json_encoder_nodoc_fix

JSON encoder internals showed up in docs [ci skip]
Use .railsrc while creating new plugin if available

- Fixes #10700
Merge pull request #10712 from prathamesh-sonpatki/plugin-railsrc

Use .railsrc while creating new plugin if available. Fixes #10700
Use genderless pronouns in security guide. [ci skip]

related  #49ff20d9b164693ed7fee880b69cc14b141678b3
Merge pull request #13126 from vipulnsward/gender_neutral_pronouns

Use gender - neutral pronouns in security guide.
[ci skip] Removing some gender sensitive object pronouns
Update API docs guidelines with reference about gender neutral pronouns