Support Specified Base Profile

[kalzoo]

The QIR Base Profile specification is nearing completion, and requires support from this SDK. While this is close to the Unitary pattern, it has some notable differences:

• Version strings
• Entrypoint specification
• Function block structure
• Use of attributes

These must be supported, likely by a new pattern.

[swernli]

As we work on supporting Base Profile on the client side, we ran into an early issue related to this:

qcs-sdk-qir/src/transform/unitary/quil.rs

Lines 73 to 81 in cd4994b

	// validate that the function returns void, as a requirement of the Unitary format
	let void_func_ty = context.base_context.void_type().fn_type(&[], false);
	let func_ty = function.get_type();
	if func_ty.ne(&void_func_ty) {
	return Err(eyre::eyre!(
	"expected function to return void; found {}",
	func_ty.print_to_string()
	));
	}

This code treats it as an error when the entry point is non-void, but with profile compliant QIR the entry point should be i64 and have a hard-coded ret i64 0.