[NEVER MERGE THIS!!!] constexpr the runtime parameters

[zingale]

PR summary

This is an experiment to see if keeping the runtime parameters as constexpr instead of managed helps with later versions of ROCm. Note: the values are compiled in, so they will need to be hacked to override the defaults for a particular problem.

PR motivation

PR checklist

• [ ] test suite needs to be run on this PR
• [ ] this PR will change answers in the test suite to more than roundoff level
• [ ] all newly-added functions have docstrings as per the coding conventions
• [ ] the CHANGES file has been updated, if appropriate
• [ ] if appropriate, this change is described in the docs

[zingale]

run this together with this Microphysics PR: https://github.com/AMReX-Astro/Microphysics/pull/1441

these hardcode the parameters for the subchandra problem, which is one of the problems that fails with later versions of ROCm

[zingale]

The way this works is that we pass --constexpr to the python scripts that write the parameters headers. This changes them to declare them as constexpr instead of (extern) managed. The values are no hardcoded in, and there are no parmparse queries for them.