gccrs: Typecheck: lifetime interning and resolution tool

gccrs: Typecheck: lifetime interning and resolution tool

gcc/rust/ChangeLog:

	* typecheck/rust-hir-type-check.h (class Lifetime): add interned lifetime class
	* typecheck/rust-typecheck-context.cc (TypeCheckContext::TypeCheckContext): add
	resolution tool
	(TypeCheckContext::intern_lifetime): add method to intern lifetime from tyctx
	(TypeCheckContext::lookup_lifetime): add method to lookup lifetime from tyctx
	(TypeCheckContext::intern_and_insert_lifetime): add a helper method

Signed-off-by: Jakub Dupak <dev@jakubdupak.com>