renderer_utils: Clean up Clang-tidy warnings Clean up various Clang-tidy warnings in renderer_utils.[cpp|h]. Most of these are around for loops: * Using const references, rather than making copies. * Using range-based for loops. There are other changes related to cleaning up ineffective const qualifiers, unused values, trivial ctors/dtors, etc. Bug: b/372694741 Change-Id: I1c88124a67a3e60537e1d5747603077f1c9cc8d3 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/6244613 Commit-Queue: Tim Van Patten <timvp@google.com> Reviewed-by: Cody Northrop <cnorthrop@google.com>