GEOMESA-552, 553 Refactor GeoMesaCoverageReader to utilize functionality in geomesa-raster, create class to hold GeoMesaCoverageReader parameter values

Removed redundant code in GeoMesaCoverageReader to instead use code in the geomesa-raster project. Also moved code from geomesa-plugin to geomesa-raster to better structure and organize the project. Added a class to store GeoMesaCoverageReade GeneralParameterValues to aid in queries for raster images.
I'm not introducing the padding, just moving values from one place to another. Here's where it had been before: https://github.com/locationtech/geomesa/pull/389/files#diff-9227e495473fc6c740701aaca78ff29cL90