Remove or rename runtime_opts.F90

### Issue Type

Code Clean-up

### Issue Description

Currently in CAMDEN there is both a `runtime_obj.F90` and `runtime_opts.F90` module, with the `runtime_opts.F90` containing now only the `read_namelist` subroutine.

I find it confusing to have two "runtime options" modules. Thus it seems like it would be cleaner if either `read_namelist` is added to `runtime_obj` and remove `runtime_opts`, or just rename `runtime_opts` to `read_namelist`.

### Will this change answers?

No

### Will you be implementing this yourself?

Any Software Engineer can do this