Use `NA` in data sharing progress report table where appropriate based on repository

[abnerbog]

Jordan pointed out this out 2/18 CI call. Some fields in this table should be NA instead of zero based on the repository:

clusters	provider	num_discoverable	num_public	num_published	num_unknown
Big Data Cluster	HydroShare	0	1	0	0
Coastal Cluster	HydroShare	0	0	13	0
Dust^2 Cluster	Zenodo	0	0	0	1
All	All	0	1	13	1

Fields that should be NA based on provider:

• EarthChem: num_public, num_unknown
• HydroShare: num_unknown
• Anything other than EarthChem or HydroShare (e.g., Zenodo, FigShare): num_discoverable, num_public, num_published