Reduce CAM initialization memory footprint that is important for ne1024 simulation- #4102

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This PR reduces the memory usage during CAM initialization by adding a new module named cam_shmem_mod.F90, which allocates the read-only looku tables once per shared-memory node and maps it into every rank on that node.

Then the following modules are updated to reduce duplicated fields/tables:

• mo_jlong — xsqy, rsf_tab, xs_o2b/o3a/o3b. Also changes the bulk broadcast from all-ranks to leaders-only, cutting the inter-node broadcast volume.
• phys_prop — the modal, hygroscopic and volcanic-radius aerosol-optics tables.
• soil_erod_mod — the source-grid erodibility field, now read on masterproc only.
• tracer_data — one per-file buffer holding the global lat-lon source field in flight, so the node leader reads each field once instead of every rank reading it redundantly. Files already on the unstructured physics grid and zonal-average files are unaffected.

A few additional updates:

• New finalization path (jlong_final, photo_final, physprop_final) so the windows are freed collectively from chem_final/phys_final.
• cam_shmem_init() is called early in cam_init so the first MPI_Comm_split_type(SHARED) is paid at a controlled collective point rather than mid-physprop.
• Initial-condition and topo files are closed at the end of cam_init, after their last use in phys_init, instead of being held open until cam_final.
• tracer_data carries the overlapping time record forward in memory when the bracketing window advances by one record, instead of re-reading it.

This PR is done by Claude code under my supervisory.

Fixes #1640

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@cacraigucar @jtruesdal this file is generic and not specific to CAM. My suggestion is to merge this PR with it for now (after addressing all the review comments). After that I will merge this code with a similar one in CTSM (ESCOMP/CTSM#4102), and bring it into CESM_share instead. Once we have a new CESM_share tag and bring it into CAM, we can then safely remove this code later.