OMPT Target Offload Support (#17)

- Porting from https://github.com/ROCm/omnitrace/pull/411
- Improve OMPT support
- Add OpenMP target example to testing
- Update Timemory submodule to use ROCm/Timemory rather than NERSC/Timemory
- Update `actions/upload-artifacts` to v4
- Standardize the `cmake_minimum_required` to 3.18.4 across workflows, project, and examples
- Updated Ubuntu 20.04 workflows

[ROCm/rocprofiler-systems commit: 9da7365471]

projects/rocprofiler-systems/examples/user-api/CMakeLists.txt

@@ -1,4 +1,4 @@
-cmake_minimum_required(VERSION 3.16 FATAL_ERROR)
+cmake_minimum_required(VERSION 3.18.4 FATAL_ERROR)
 
 project(rocprofiler-systems-user-api-example LANGUAGES CXX)