Convert an aro.Source.Location to a 'file:line:column' string.
pub fn locStr(t: *Translator, loc: aro.Source.Location) ![]const u8
pub fn locStr(t: *Translator, loc: aro.Source.Location) ![]const u8 {
const expanded = loc.expand(t.comp);
const filename = expanded.path;
const line = expanded.line_no;
const col = expanded.col;
return std.fmt.allocPrint(t.arena, "{s}:{d}:{d}", .{ filename, line, col });
}