Improve testing error locations

[asterite]

Right now in the compiler's frontend tests we just check that expected errors happen. However, we don't check where they happen.

One way to do this would be in a way similar to how it's done in parser tests:

noir/compiler/noirc_frontend/src/parser/parser/statement.rs

Lines 711 to 724 in 8783e48

	#[test]
	fn errors_on_return_statement() {
	// This shouldn't be parsed as a call
	let src = "
	return 1
	^^^^^^^^
	";
	let (src, span) = get_source_with_error_span(src);
	let mut parser = Parser::for_str(&src);
	let statement = parser.parse_statement_or_error();
	assert!(matches!(statement.kind, StatementKind::Error));
	let reason = get_single_error_reason(&parser.errors, span);
	assert!(matches!(reason, ParserErrorReason::EarlyReturn));
	}

That is, allow squiggles bellow a line, pre-process that input and extract the span where the error would happen.