noresm3_0_023_cam6_4_121: CAM7 physics now uses new CMIP7 nitrogen deposition

[mvertens]

Summary:
cam7 physics now uses new cmip7 nitrogen deposition

Contributors: mvertens

Reviewers: @gold2718

Detailed description of changes:

• New nitrogen deposition data in $DIN_LOC_ROOT/atm/ndep/cmip7 is now used when cam7 physics is on.
• New namelist variable stream_ndep_varlist has been added which is a colon delimited string of the variable names that are on the file.
  • for physics that is not cam7 the value is NDEP_NHx_month:NDEP_NOy_month and it is assumed that the units are g/m2/sec and a scaling of .001 is applied in atm_stream_ndep.F90 to convert to kg/m2/sed
  • for physics that is cam the value is drynhx:wetnhx:drynoy:wetnoyand it is assumed that the units are kg/m2/sec so no scaling is applied in atm_stream_ndep.F90

Changes made to build system: None

Changes made to the namelist: Yes (see description above)

Changes to the defaults for the boundary datasets: Yes (for nitrogen deposition if physics is cam7)

Substantial timing or memory changes: should be none

Testing: ran aux_cam_noresm and compared to noresm3_0_022_cam6_4_121. The only differences were the fields atmImp_Faxa_ndep1 and atmImp_Faxa_ndep2 in the cpl.hi files where cam7 physics was used.

Issues addressed by this PR: NorESMhub/NorESM#742

@JorgSchwinger - with this PR cam will use the cmip7 nitrogen deposition datasets by default when cam7 physics is used in the simulations (which is the case for all of our current NorESM3 runs).

[gold2718]

This looks pretty good, I just have a suggestion and one request to move a default entry.

[gold2718]

Looks good now, thanks!