Fix breakage in XmlMini

- Boolean parsing breaks on non strings (i.e. integer 1|0)
- Symbol parsing breaks on non strings.
- BigDecimal parsing breaks due to missing require.
- Update changelog.
psql implementation of #index_name_exists?
Do not discard query parameters on requests that use wrap_parameters
Maintain the current timezone in wrap_with_time_zone

Extend the solution from the fix for #12163 to the general case where
`Time` methods are wrapped with a time zone.

Fixes #12596.
FilterRedirect is referenced at the class level from the Response

We can just require the file rather than going through the autoload
indirection
only ask for the location filters once
just require the template resolver

LookupContext is eagerly loaded, and FallbackFileSystemResolver is
referenced at the class level.  Just require the resolver from the
eagerly loaded class rather than jumping through autoload hoops
this class depends on JoinHelper, so we should require it
Fixes issue with parsing whitespace content back from database - fixes #13907
Merge pull request #12769 from birkirb/master

Boolean parser blows up on a Fixnum.

Conflicts:
	activesupport/CHANGELOG.md
Merge pull request #13912 from mauricio/bug-13907

Fixes issue with parsing whitespace content back from database - fixes #13907
Merge pull request #13863 from joshjordan/jsj-dont-throw-out-get-params

Do not discard query parameters on requests that use wrap_parameters

Conflicts:
	actionpack/CHANGELOG.md
Merge pull request #13688 from jbaudanza/psql-index-exists

PostgreSQL implementation of SchemaStatements#index_name_exists?

Conflicts:
	activerecord/CHANGELOG.md
Make arel methods private API

Since its conception arel was made to be private API of Active Record.
If users want to use arel features directly we should provide a way
using the Active Record API without exposing the arel implementation.
Remove warnings for already defined methods
Don't require BigDecimal serialization extension

Rails currently provides an extension to BigDecimal that redefines how
it is serialized to YAML. However, as noted in #12467, this does not
work as expected. When ActiveSupport is required, BigDecimal YAML
serialization does not maintain the object type. It instead ends up
serializing the number represented by the BigDecimal itself which, when
loaded by YAML later, becomes a Float:

```ruby
require 'yaml'
require 'bigdecimal'

yaml = BigDecimal('13.37').to_yaml
YAML.load(yaml).class

require 'active_support/all'

yaml = BigDecimal('13.37').to_yaml
YAML.load(yaml).class
```

@tenderlove posits that we should deprecate the custom BigDecimal
serialization and let Ruby handle it. For the time being, users who
require this serialization for backwards compatibility can manually
`require 'active_support/core_ext/big_decimal/yaml_conversions'`.

This will close #12467 and deprecate the custom BigDecimal#to_yaml.

Signed-off-by: David Celis <me@davidcel.is>
Remove BigDecimal#to_d

This was backported for Ruby 1.8 support and is no longer needed.

Signed-off-by: David Celis <me@davidcel.is>
Merge pull request #13911 from davidcelis/remove-bigdecimal-serialization

Deprecate custom BigDecimal serialization

Conflicts:
	activesupport/CHANGELOG.md
Fix isolated tests
Assert the file is deprecated