Delete zero-caller public interfaces from MAPL_Base (#4806)

* Delete zero-caller public interfaces from MAPL_Base (#4805)

Removes ~1800 lines of dead code from Base_Base.F90 and
Base_Base_implementation.F90. All interfaces with active callers
are retained. Fixes #4805.

* Fix ifort CI: restore missing module procedure declarations in Base_Base.F90

ifort requires that all module subroutine/function procedures implemented in a
submodule have a corresponding interface declaration in the parent module, even
if the procedure is private. Restore the 5 missing declarations:
- MAPL_FieldAllocCommit
- MAPL_TimeStringGet
- MAPL_FieldCreateEmpty
- MAPL_FieldCopy
- MAPL_GetGlobalHorzIJIndex

* Delete test_Mapl_Base.pf — tests MAPL_Leap and MAPL_DecomposeDim which were removed from public interface

* Re-export MAPL_PackTime/UnpackTime from Base.F90 — external callers in GMAO_Shared still use these via MAPL2/MAPL

Author: tclune

base/Base.F90

@@ -8,6 +8,8 @@ module MAPLBase_Mod
   use MAPL_BaseMod, only: MAPL_GRID_INTERIOR
 ! For temporary backward compatibility after moving/renaming:
   use MAPL_BaseMod, only: ESMF_GRID_INTERIOR => MAPL_GRID_INTERIOR
+! PackTime/UnpackTime removed from Base_Base but still have external callers:
+  use mapl3g_TimeUtilities, only: MAPL_PackTime => PackTime, MAPL_UnpackTime => UnpackTime
    use NCIOMod
   use MAPL_LocStreamMod
   use MAPL_ShmemMod