Need to move ccpp_io_reader to its own directory

CAM currently builds all the files in the `phys_utils` directory, as functions there are needed elsewhere in CAM. However, that currently means the `ccpp_io_reader.F90` file, which is not used at all in CAM, is also being built, which is causing problems with the out-of-date NAG compiler being used for regression testing.

This problem can be fixed by simply moving `ccpp_io_reader.F90` to it's own top-level directory, maybe something like `sima_utils` or `ccpp_utils`, to help make sure that CAM doesn't attempt to build this source code.

Also, please note that this change will require a change in CAM-SIMA where this new directory is _always_ included in the build, which can be done by simply replacing `phys_utils` with the new directory in the CAM-SIMA configuration code found here:

https://github.com/ESCOMP/CAM-SIMA/blob/development/cime_config/cam_autogen.py#L641-L658

Start with ccpp_io_reader.F90 in the phys_utils directory and inspect how CAM currently includes that directory. Then review CAM-SIMA's cime_config/cam_autogen.py around lines 641-658. Done means the reader has its own top-level directory, CAM no longer builds it through phys_utils, and CAM-SIMA always includes the new directory.

Written by the indexing model from the issue text.