Project: add visibility attribute

[joewheaton]

@ybakos we had an interesting request from Erica Fifer, to have the option of using LTPBR Explorer to report projects, but to hide these to projects from the public such that:
a) they don't show up on the map (or are potentially geo-scrambled)
b) they still get included in credit by State and Organization for total structures and miles
c) they are only accessible to those logged in with permision

I think this is likely to be a feature we would only provide behind a paywall (unless NRCS or USFWS want to pay for it), but I would be curious to scope its cost. It comes up a lot with NRCS and USFWS over concerns about privacy for private landowners. I think it is often assumed it is going to be an issue, and it is not always. All the same, this is worth thinking about.

Thoughts @nick4rivers?

[ybakos]

@joewheaton Thanks for that info. It is a relatively simple feature to implement, I'll send you scope/cost via email.