Add permanent storage option for EventStream

[rbren]

This allows EventStream to persist to a local or remote filesystem, instead of keeping all state in-memory.

This is helpful for a high-availability situation. For example, currently, if you rolled out a new deployment, any websockets would be disconnected, existing user sessions would be cancelled, and all the session data would be lost.

With this change, the client could reconnect to a new instance of the application, and the EventStore could rehydrate from persistent storage.

This change also factors action/observation/event serialization and deserialization into its own spot, to avoid circular imports

[assertion]

@rbren I found this bug when opening two browsers and chat with opendevin at the same time, the bug related to EventStream. pr: https://github.com/OpenDevin/OpenDevin/pull/1713

And I found you fixed it in current pr, but I suggest to merge mine pr before you finish current one.

[rbren]

good catch @assertion!

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 83.69565% with 45 lines in your changes are missing coverage. Please review.

:exclamation: No coverage uploaded for pull request base (main@755a407). Click here to learn what that means.

Files	Patch %	Lines
opendevin/server/agent/agent.py	0.00%	10 Missing :warning:
opendevin/storage/s3.py	55.55%	8 Missing :warning:
opendevin/events/serialization/event.py	85.71%	7 Missing :warning:
opendevin/events/serialization/action.py	77.77%	6 Missing :warning:
opendevin/storage/files.py	71.42%	4 Missing :warning:
agenthub/dummy_agent/agent.py	33.33%	2 Missing :warning:
opendevin/events/serialization/observation.py	91.66%	2 Missing :warning:
opendevin/runtime/server/runtime.py	0.00%	2 Missing :warning:
opendevin/storage/__init__.py	85.71%	2 Missing :warning:
opendevin/controller/agent_controller.py	0.00%	1 Missing :warning:
... and 1 more

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1697   +/-   ##
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  Coverage        ?   61.37%           
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  Files           ?      108           
  Lines           ?     4241           
  Branches        ?        0           
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  Hits            ?     2603           
  Misses          ?     1638           
  Partials        ?        0           

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[enyst]

I haven't got to test it, otherwise LGTM!