Refactor kgof module

[darsh-patel]

Is your feature request related to a problem? Please describe.
The current state of the GoF Module is such that it takes a Data object wrapping a numpy array as input. For the module to match the remainder of the library, it needs to take numpy arrays as inputs. Additionally, new kernel support must be added to ensure the module covers a variety of different use cases.

Describe the solution you'd like

• The FSSD class that inherits from the base class includes extraneous helper methods: Does not match the style of the child classes present in the rest of the library; There is a circular import involved if one attempts to remove the helper methods from the child class; Will require an in-depth rip-and-replace
• Kgof currently takes inputs in the form of a Data object – an object encapsulating a 2-dimensional numpy array: The Data object also contains a synthetic “Datasource” that allows for a resampling of data; Does not match with the inputs for the remainder of the library
• The module structure revolving around kernel sources and density sources contains code that is redundant with other things in hyppo: Remove this code and replace it with what has already been written

Describe alternatives you've considered

Additional context (e.g. screenshots)

[darsh-patel]

Please assign when you have a chance @sampan501