feature(cache): explore using fastapi-cache to cache responses

[jhamman]

This is an alternative to #42 and one that aligns much closer with @mpiannucci's comment in #40 (comment).

TODOs:

• figure out how to support plugable fastapi-cache backends (or no caching at all)
• add tests

[abkfenris]

I'd probably add a cache_uri parameter to the plugin to configure cache type and connection information.

class CfEdrPlugin(Plugin): 
     """ 
     OGC EDR compatible endpoints for Xpublish datasets 
     """ 
  
     name: str = "cf_edr" 
  
     ...

    cache_uri: Optional[str] = None  # could be 'inmemory', 'redis://...'

But it might be something that would be better to have as a top level Xpublish dependency and configuration option, then all plugins can take advantage of it (at least for formats where CDNs make sense).