[Draft][GSProcessing] Improve Spark config to better support EMR/EMRS, small optimizations

[thvasilo]

Issue #, if available:

Description of changes:

• We change the way we configure the Spark env, to only create our own config for SageMaker, as EMR/EMRS will have pre-configured defaults.
• We introduce some enum classes to better communicate execution environment and filesystem type
• We try to cache DFs that are used multiple times to avoid re-computation
• Do not use : in the data paths, as it can cause errors when moving the data to local filesystems.

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