Cleanup of omega broadcast and time mgr to remove warnings

[philipwjones]

• changes method for retrieving char ptr for string bcast
• removes some unnecessary warnings from time mgr
• updates some related test drivers for consistency and to conform to coding conventions

Checklist

• Linting
  • Pre-commit run locally
• Building
  • CMake build does not produce any new warnings from changes in this PR
• Testing
  • Add a comment to the PR titled Testing with the following:
    • Which machines CTest unit tests
      have been run on and indicate that are all passing.
    • The Polaris omega_pr test suite
      has passed, using the Polaris e3sm_submodules/Omega baseline
    • Document machine(s), compiler(s), and the build path(s) used for -p for both the baseline (Polaris e3sm_submodules/Omega) and the PR build
    • Indicate "All tests passed" or document failing tests
      after.

Fixes #336
Fixes #292

[philipwjones]

Passes all ctests on pm-cpu and pm-gpu