Expose new MAPL field bundle subroutines via "use MAPL"

[bena-nasa]

Larry needs to use my MAPL_read_bundle subroutine (replacement for MAPL_CFIORead) as the current MAPL_CFIORead chokes on our current cubed sphere files (this is needed for R21C as they have some cubed-sphere precip correction files to read) and the simple solution is to use the routine I made to replace MAPL_CFIORead. When he tried this in a few GEOS gridcomps, I found out that apparently "use MAPL" does not expose this so I'm updating MAPL.F90 to expose this.

Description

Related Issue

Motivation and Context

How Has This Been Tested?

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Trivial change (affects only documentation or cleanup)

Checklist:

• I have tested this change with a run of GEOSgcm (if non-trivial)
• I have added one of the required labels (0 diff, 0 diff trivial, 0 diff structural, non 0-diff)
• I have updated the CHANGELOG.md accordingly following the style of Keep a Changelog