Add support for simple type annotations in parser and update llhello sample with a possible new low-level dialect syntax leveraging those annotations

{
	foo <- { 42 }
	#{
		qux <- foo:
		bar <- #{
			
			baz <- {
				foo:
			}
			
		}
		
		main <- {
			print: (string: (bar baz))
		}
	}
}