Add member function implementation stubs using reflection

[jbcoe]

Adds stubs for member function to both protocol and protocol_view. Stub member functions cannot be called (there is currently no vtable to forward calls), but their signatures can be checked at compile-time.

[RyanJK5]

Good work! The core of it seems to be functioning nicely :)

[RyanJK5]

Good progress, I tagged a few things that I missed in my initial review.

[RyanJK5]

This approach is a bit less noisy and reduces some of the heavyweight template instantiations that come from template for (may not be perfect):

Suggested change

	template for (constexpr std::meta::info member : std::define_static_array(
	std::define_static_array(
	members_of(InterfaceType,
	std::meta::access_context::unprivileged())) |
	std::views::filter(std::meta::is_function) |
	std::views::filter(
	std::not_fn(std::meta::is_special_member_function)) |
	std::views::filter(
	std::not_fn(std::meta::is_static_member)) |
	std::views::filter(std::meta::has_identifier))) {
	member_base_types.push_back(
	^^typename member_base_generator<member>::member_base);
	}
	for (std::meta::info member : members_of(InterfaceType, std::meta::access_context::unprivileged()) |
	std::views::filter(std::meta::is_function) |
	std::views::filter(std::not_fn(std::meta::is_special_member_function)) |
	std::views::filter(std::not_fn(std::meta::is_static_member)) |
	std::views::filter(std::meta::has_identifier)) {
	member_base_types.push_back(dealias(substitute(^^member_base_generator_t, {reflect_constant(member)})));
	}

It would require adding:

template <std::meta::info Member>
using member_base_generator_t = member_base_generator<Member>::member_base

[RyanJK5]

Isn't this behavior incorrect? I thought protocol_view used shallow const, so a const protocol_view should be able to call update, whereas a protocol_view<const Interface> should not.

[RyanJK5]

Since this is producing a static array anyway, I think it makes sense to make this a variable template. That way the results are cached if this is ever called again.

Suggested change

	consteval auto protocol_interface_functions_of() {
	return std::define_static_array(
	std::define_static_array(
	members_of(Type, std::meta::access_context::unprivileged())) |
	std::views::filter(std::meta::is_function) |
	std::views::filter(std::not_fn(std::meta::is_static_member)) |
	std::views::filter(std::meta::has_identifier));
	}
	constexpr inline auto protocol_interface_functions_of = std::define_static_array(
	members_of(Type, std::meta::access_context::unprivileged()) |
	std::views::filter(std::meta::is_function) |
	std::views::filter(std::not_fn(std::meta::is_static_member)) |
	std::views::filter(std::meta::has_identifier));

NOTE: I also dropped the inner define_static_array, which I believe was unnecessary. Please add it back if I am mistaken.

[RyanJK5]

Related to my comment on the NonConstMemberFunctionNotInvocableFromConst test: I believe this is incorrect. protocol_view<I> should inherit from a slightly different version of protocol_stubs_t where every member function is const regardless of whether or not it was const in the interface. Later on, protocol_view<const I> would inherit from a protocol_stubs_t that filters out all of the non-const functions as well.