Implement data field checks

[AdamRJensen]

Country names should be in this list (with some exceptions, e.g., Reunion): https://en.wikipedia.org/wiki/List_of_alternative_country_names

• [x] Latitude should be within +/- 90 degrees
• [x] Longitude should be within +/-180 degrees
• [x] Elevation should be within -300 and 9000 m
• [x] Country should checked (#202)
• [x] Data availability should be either: Freely, Upon request, Not available, or blank/None #204
• [ ] Acronyms should not be duplicated
• [ ] Instruments should be in G, B, D, Ds, IR, UVA, UVB, UV, PAR, SPN1, RSR, RSI, RSP]

For old metadata formatting (prior to merging of columns described in #111)

• Tier should either be 1 or 2
• Instrument types should be in list: [Thermopile, SPN1, RSR, RSI, RSP]
• Components should be in [G, B, D, IR, UVA, UVB, UV, PAR]

This will help ensure consistent naming and acts as a pre-review and save reviewing time

[kandersolar]

143 includes some of these checks (lat, lon, elevation) and is designed in such a way to make it easy to add additional checks

[IoannisSifnaios]

I think the options for data availability should be: Freely, Upon request, and Not available.

Leaving it blank/None just makes it more confusing...