[FEA]: Adopt Clang19

[dagardner-nv]

Is this a new feature, an improvement, or a change to existing functionality?

Improvement

How would you describe the priority of this feature request

Medium

Please provide a clear description of problem this feature solves

This would allow a few things:

1. Adopt an updated version of IWYU with ARM support
2. Pickup the fix for [BUG][clang-tidy-diff] SyntaxWarning: invalid escape sequence llvm/llvm-project#92948 and remove the -W ignore flag being set in ci/scripts/cpp_checks.sh

Describe your ideal solution

Adopt Clang 19

Describe any alternatives you have considered

No response

Additional context

No response

Code of Conduct

• I agree to follow MRC's Code of Conduct
• I have searched the open feature requests and have found no duplicates for this feature request