Adds geographically weighted regression analyses (describe and predict)

[andy-esch]

For new analysis use the following checklist:

• Uses the_geom geometry(Geometry, 4326) column for all geospatial operations.
• Outputs a the_geom geometry(Geometry, 4326) column.
• Outputs a cartodb_id numeric column.
• Uses {cache: true} option when it needs full knowledge of the table it. Hints: aggregations, window functions.
• Uses {cache: true} if it access external services.
• Naming uses a-z lowercase and hyphens.
• All mandatory params cannot be made optional.
• Avoids using CTEs for join operations when result is not cached.

[jgoizueta]

Before merging/releasing this, please check with me @andy-esch, we have released a version of camshaft that needs some fixing before being used

[andy-esch]

Thanks @jgoizueta, I'll take a look 👍

[andy-esch]

We might pause on this for a while until we know it will get the Builder Analysis interface created as well. Until then we're going to create dep sql node for this instead.