Pacer integration into Omega standalone driver

[sarats]

This PR adds Pacer timing API and top-level timers to the standalone Omega driver. It includes CMake logic to build and link with Pacer and GPTL.

This PR depends on upstream E3SM PR: https://github.com/E3SM-Project/E3SM/pull/6772 So, we need to sync the Omega repo with upstream once the above PR is merged into E3SM. Then this PR brings in the timing functionality to Omega.

Checklist

• [X] Documentation and Testing: Additional details and testing with standalone driver on Frontier is at https://acme-climate.atlassian.net/wiki/spaces/OO/pages/4775346241/Pacer+timing+interface

[sarats]

trim trailing whitespace.................................................Failed

AFAIK, I checked the standalone driver and haven't added any trailing whitespace. So, not sure why the pre-commit hook is complaining.