Fixed JSON request had 1 or 0 array elements and add json_parameters method

[kfly8]

This pull request solves the following problems.

Problem

When requesting JSON with one or zero array elements, the body parameters are no longer an array:

Case: POST { b => [123] }
Then: { b => 123} 
Expected body parameters : { b => [123] }

Case: POST { b => [] }
Then: {} 
Expected body parameters : { b => [] }

The following test code reproduces this problem. t/100_bugs/002_a_few_parameters_in_json_body.t

Solutions

1. Decode body parameters recursively.
2. Added json_parameters method for easier handling of JSON requests.

[kfly8]

This change reverts back to the v0.60 code.

Kossy/lib/Kossy/Request.pm

Lines 155 to 161 in 4191730

	sub body_parameters_raw {
	my $self = shift;
	unless ($self->env->{'plack.request.body'}) {
	$self->env->{'plack.request.body'} = Hash::MultiValue->new(@{$self->_body_parameters});
	}
	return $self->env->{'plack.request.body'};
	}

[kfly8]

For application/x-www-form-urlencoded and
multipart/form-data, but not the get_all method for application/json.

I think this is fine for this test, but essentially, I consider this a non-intuitive behavior.

Therefore, I would like to add a method called json_parameters to simplify the handling of JSON requests.

[kfly8]

I think the reason for using Hash::MultiValue is to handle Arrays.

If JSON can handle structures such as Arrays, so I prefer to not using Hash::MultiValue.

[kfly8]

When using json_parameters accessor, this setting is no longer necessary for simplicity.