This commit creates a new ConfigAdapter used in vector maps instantiations.
This adapter generates a new sql query for ONE SINGLE LAYER (carto-vl currently only supports one layer per mvt)
where the date columns are wrapped into a epoch using the `date_part` function.
Due this mvt files are smaller since we use numbers instead strings to represent dates, this is also faster in carto-gl
where we interpolate linearly between 0 and 1 to create animations.
Notice we should add a parameter to make this transformation optional.
We also should take into account the epoch precission.
The sampling probability is now being computed using an estimate of the table row count
This could led to too high probabilities (to large samples) if the estimate is not accurate.
To avoid potential problems with large samples we've added a LIMIT to the sampling queries.
