Move fvcore_layout.rc to FV3?

[mathomp4]

This is mainly a meta-question for @wmputman, but I've always wondered: why is fvcore_layout.rc here in GEOSgcm_App? To me it seems more suited to the FV3 directory as in most of the rest of GEOS, we keep RC files with their source code (see GOCART).

It wouldn't be too hard to change, just a file move and updates to a couple CMakeLists.txt files.

[wmputman]

Initially I have no problems changing this location, but for certain 'apps' (like various standalone FV3 configurations and tests) we might prefer a different layout configuration.

[tclune]

@wmputman Any 'apps' that use FV would have access to the fvcore_layout.rc file. It's just a question of where the default settings live. The actual build can still copy the resource file into whatever build/install directory the app expects to find it in

The issue goes beyond just FV. Now that the GEOSgcm app is a separate repo, we will be aggressively trying to refactor bits of the app into the components to reduce the frequency of changes that span multiple repositories.