Promote usage of "connection" and deprecate "session"

Currently in the python client implementation and examples, the terms "session" and "connection" are used interchangeably.

I think it would improve usability and reduce confusion if only one of them would be used.

Some arguments to favour "connection" and deprecate "session"

• the openeo client guidelines use "connection", not "session"
• "connection" is pretty explicit about being connected to a particular backend and acts as the starting point to interact with that backend. The term "session" is more general and could (also) be a container for non-backend related settings (e.g. where data files should be downloaded to, where user credentials are stored, ...). And maybe in longer term, a session could also be about maintaining multiple connections to possibly different backends. Also see sqlalchemy for example where "session" is a higher level, more encompassing thing than "connection".
• the Python DB API (PEP249) uses the term "connection"

Review the Python client implementation and examples for uses of “session” and “connection”, then compare the terminology with the linked openEO client guidelines and PEP 249. The scope and compatibility implications are not defined; done should mean a decided, consistent terminology across the affected client surface and examples.