ENH: Fix to resolve #750 for older ARM qc convention in files

[AdamTheisen]

• Closes Error while using add_dqr_to_qc: flag_values and flag_masks not set as expected #750
• Tests added
• Documentation reflects changes
• PEP8 Standards or use of linter
• Xarray Dataset or DataArray variable naming follows 'ds' or 'da' naming

[AdamTheisen]

@kenkehoe @zssherman I think i have a fix in and working for the Old QC standards (or lack of standards that is). Let me know what you think.

[kenkehoe]

Looks good. Do you need to set the Dataset variable big_#description and bit#_assessment attributes? We don't set those for other QC variables when we use flag_values, flag_meanings, flag_assessents.

[AdamTheisen]

Looks good. Do you need to set the Dataset variable big_#description and bit#_assessment attributes? We don't set those for other QC variables when we use flag_values, flag_meanings, flag_assessents.

@kenkehoe good question. I thought there was an error when I did but I ran it without it and worked. I'll remove that to simplify things