EAMxx: reorganize eamxx libraries (part 9)

[bartgol]

Ninth (and possibly final) step of the reorg: diagnostics lib and share lib

[BFB]

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Summary:

• All the eamxx targets are now declared in the same order in which they are used (meaning each target only depends on previously defined targets), making the eamxx/src folder structure more linear.
• The diag lib is not part of the share lib, so that it gets parsed before the IO folder (which needs it only in unit tests, tbh).
• The diag lib is renamed (prefixed with eamxx_), to avoid name clashing with other cmake targets.
• Data/time interp are now part of eamxx_io. For time interp, this may be debatable, as it supports the case where the fields are not read from file.
• The share lib is not officially just an interface target, that wraps together all targets defined in the share folder.

Looking forward to possible reorgs of files:

• data/time interp (along with scorpio_input) may be moved to data_managers, and eamxx_io may be fully dedicated to writers functionalities.
• diagnostics may be built as part of the eamxx_io lib, as they are ONLY used there. I am somewhat not fond of this, as I can foresee atm procs using diags to compute common utility fields (e.g., z_mid), and only do so if the inputs timestamp has changed.
• the eamxx_physics_share lib may be renamed something like eamxx_common_physics
• the PhysicsFunction struct and the common_physics_functions header may be unified in a single common physics header

NOTE: if the move of data/time-interp and scorpio input to eamxx_data_managers seems reasonable, I would prob do it here, so that we don't change the data/time interp location just to change it soon afterwards...

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[tcclevenger]

I'm ok if you want to move to data_managers here. I'm out of work tomorrow, so I'll go ahead and approve if you want to merge instead.