feat: Custom property classes

[ForTheYin]

I was looking into creating a custom property class to try and output OpenAPI / Swagger schema, but I couldn't get the keyword arguments to pass into my new class. This change adds **kwargs to the prop constructor so that downstream modules / classes can send additional args to the custom property class.

Changes

• Add **kwargs to Literal::Properties.prop
• Tests for custom property classes

Example

class DescriptionProperty < Literal::Property
	def initialize(description: nil, **kwargs)
		super(**kwargs)

		@description = description
	end

	attr_reader :description
end

module DescriptionProperties
	def prop(name, type, kind = :keyword, description: nil, **, &coercion)
		super
	end

	def __literal_property_class__
		DescriptionProperty
	end
end

class Example < Literal::Object
	extend DescriptionProperties

	prop :name, String, description: "The person's name"
	prop :age, Integer, description: "The person's age"
end

# irb:> Example.literal_properties
# =>
#   #<Literal::Properties::Schema:0x0000000120e6d6f8
#   @mutex=#<Thread::Mutex:0x0000000120e6c618>,
#     @properties_index=
#       {name: #<DescriptionProperty:0x00000001217fadd8 @coercion=nil, @default=nil, @description="The person's name", @kind=:keyword, @name=:name, @predicate=false, @reader=false, @type=String, @writer=false>,
#          age: #<DescriptionProperty:0x00000001217f97f8 @coercion=nil, @default=nil, @description="The person's age", @kind=:keyword, @name=:age, @predicate=false, @reader=false, @type=Integer, @writer=false>},
# @sorted_properties=
#   [#<DescriptionProperty:0x00000001217fadd8 @coercion=nil, @default=nil, @description="The person's name", @kind=:keyword, @name=:name, @predicate=false, @reader=false, @type=String, @writer=false>,
#   #<DescriptionProperty:0x00000001217f97f8 @coercion=nil, @default=nil, @description="The person's age", @kind=:keyword, @name=:age, @predicate=false, @reader=false, @type=Integer, @writer=false>]>