Fixes #2244. Add print of regrid method to history init

[mathomp4]

Description

Adds a print of the regrid method to the history initialization prints:

 Initializing Output Stream: geosgcm_prog
 ---------------------------
       Format: CFIO
         Mode: instantaneous
       Slices:          483
      Deflate:            1
    Frequency:        60000
     Ref_Date:     20000414
     Ref_Time:            0
     Duration:        60000
  Regrid Mthd: bilinear
  Output RSLV:           96          49
    XY-offset:            0   (DcPc: Dateline Center, Pole Center)
      Fields: PHIS SLP U V T PS H OMEGA QV QI QL RH O3 PLE
...

I added that Regrid Mthd line. The weird wording is because I wanted to keep the colons lined up. 😄

Related Issue

Closes #2244

Motivation and Context

Might as well print out what type of regridding is being used.

How Has This Been Tested?

I ran GEOS. Didn't crash, zero-diff, and the print appeared.

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

[tclune]

Were we not going to do a major refactoring, I'd push for pflogger.