Feat/memory2 - plotting, examples, recorder module, semantic search

[leshy]

• adds data_type attribute to observations
• adds raw storage of strings or numbers directly into metadata store (doesn't require separate fetch and blob store)
• adds basic memory module (module that inits a db for you) and a Recorder and Query/Embedding module as example
• adds 3d projections for a whole set of detections (ImageDetections2D -> ImageDetections3DPC) as opposed to previously singular ImageDetection2D -> ImageDetection3D
• implements a new TimedSensorReplay shim that uses memory2 (our full reply file is down to 200Mb compressed vs 2Gb!)
• switches over legacy tests to LegacyPickleStore (will delete dimos/memory soon entirely and deal with pickle files)
• adds many examples to docs for memory
• removes a test that ensures all modules have start and stop (was annoying to add boilerplate, especially now with CompositeResource and automatic detection of thread leaks we have)