Symlink instead of copy the mod_def.ww3 input in the cesm_cmeps driver

[dougiesquire]

The WW3 model definition file input needs to be in the work directory and called mod_def.ww3. Previously this driver looked for a file in the inputs with "mod_def.ww3" in the filename and then copied that file to the work directory. This is bad practice. Now, the name of the file is assumed to be "mod_def.ww3" and this file is symlinked instead. Those setting up the configuration will need to ensure that a file with the right name is included in the inputs (e.g. using a symlink if the original input has a different name).

Closes #365

[pep8speaks]

Hello @dougiesquire! Thanks for updating this PR. We checked the lines you've touched for PEP 8 issues, and found:

There are currently no PEP 8 issues detected in this Pull Request. Cheers! 🍻

Comment last updated at 2023-09-29 00:30:14 UTC

[coveralls]

coverage: 42.016%. remained the same when pulling 7878fba on dougiesquire:365_cesm_cmeps_ww3_input into 2d16f18 on payu-org:master.

[aidanheerdegen]

Just a quickie question to make something clear, otherwise fine to merge if that is not something that can be changed.

[aidanheerdegen]

Merge away.