Support passing types through keyrest

[aaronmallen]

Currently if you define a type as a record type and attempt to pass a variable having that type with a keyrest Steep will raise a InsufficientKeywordArguments error. For example:

class MyClass
  # @rbs!
  #   type option_type = { foo: String, bar: String, baz: String }

  # @rbs @options: option_type

  attr_reader :options #: option_type

  # @rbs () -> void
  def initialize
    @options = { foo: 'foo', bar: 'bar', baz: 'baz' }
  end

  # @rbs (foo: String, bar: String, baz: String) -> void
  def foo(foo:, bar:, baz:)
    # ...
  end

  # @rbs () -> void
  def bar
    foo(**options) # this will cause Steep to raise InsufficientKeywordArguments
  end

  # @rbs () -> void
  def baz
    foo_options = options
    # @type var foo_options: option_type
    foo(**foo_options) # this will STILL cause Steep to raise InsufficientKeywordArguments
  end
end

It would be awesome if:

• given an ivar or variable has a type and it is a record type
  • given the record type has all the keys and types necessary to satisfy the keyword arguments
    • steep does not raise InsufficientKeywordArguments
  • given a key mismatch be it missing entirely or marked as optional when it can't be
    • steep raises InsufficientKeywordArguments
  • given a value typing mismatch (i.e. there's a String where there should be an Integer)
    • steep raises an error indicating the value types don't satisfy the keyrest operator.