Add WOMBATlite generic tracer (#1)

* initial commit

* add WOMBAT routines

* bug fixes

allocate/deallocate btf fields

remove redundant diagnostics

* enforce src info

* add unit conversions

* more bug fixes

copy no3_orig and caco3_orig directly from corresponding fields

spatially varying kmeuph

* account for absorption of sw radiation with depth

* keep only shortwave wavelengths < 710 nm

sort out units

* fix sinking bug by using internal sinking scheme

fix bug in kmeuph calculation

* fix fe units error

* fix bug with wdet100 diagnostic

* move sfc flux-related fields into WOMBAT type

* update sediment tracers via pointers

* rename to WOMBATlite

* Address Pearse's review

* Remove coupler fluxes from no3 and phy tracers

* Fix bug in radbio_int100 diagnostic

* Allow in update_from_coupler virtual flux adjustment due to salt flux restoring/adjustment

* Apply MOM6 code style

* Add ESM diagnostics