TODO: Launch support

[artv3]

This issue pulls in various reported issues to create a list of tasks.

• [x] CHAI/Plugin support (https://github.com/LLNL/RAJA/issues/1379, https://github.com/LLNL/RAJA/issues/1333) : in progress https://github.com/LLNL/RAJA/pull/1381
• [ ] Add Sycl unit test
• [x] Add dynamic shared memory unit test : in progress https://github.com/LLNL/RAJA/pull/1416
• [ ] Develop interface for perfectly nested loops, allows support for omp collapse, application requested patterns (https://github.com/LLNL/RAJA/issues/1314, https://github.com/LLNL/RAJA/issues/1346).
• [ ] add detailed examples in ReadtheDocs
• [ ] Support for new reduction interface
• [ ] Use new reduction interface instead of char pointers to handle naming
• [ ] Deduplicate exec methods - In progress here: https://github.com/LLNL/RAJA/pull/1417
• [x] Add plugin test in https://github.com/LLNL/CHAI/tree/develop/tests/integration