Support query by geographic coordinates

[dschristianson]

basin3d currently supports monitoring feature and time series queries using location identifiers.
For time series queries, the location identifier is required.

Expand basin3d to support querying by geographic coordinates.

Tasks / Key steps:

• Survey current and forthcoming data sources for location query capabilities and location return info.
• Decide desired query approach (e.g., lat/long + radius, bounding box)
• Develop any needed updates to data model(s) and add query functionality, including tests
• Migrate existing plugins to support the feature
• Update documentation