Diag_axis object missing work

[uramirez8707]

Is your feature request related to a problem? Please describe. The following things still need to be done for the diag_axis object:

• [x] set up the diag_axis_init top level #978
• [ ] explore double linked to avoid setting limits to the diag_axis_object
• [x] Add missing procedure to the diag_axis_object #982 ! PROCEDURE :: write_axis_metadata
  ! PROCEDURE :: write_axis_data
  ! PROCEDURE :: get_fileobj_type_needed (use the domain to figure out what fms2 fileobj to use)
• [x] error checking in the diag_axis_init procedure #978
• [x] subaxis setup #1056
• [x] ~move diag_copy_string~

Describe the solution you'd like N/A

Describe alternatives you've considered N/A

Additional context N/A