Feature/vector search - Githubissues

Putting this up for early review.

What does this PR do

Introduces marqo DB as the events backend
Migrates away from DynamoDB for events (we still use it for SeshuSessions at minimum, so we don't need to entirely remove Dynamo as we're using it)
Wires up X-Mnm-Subdomain-Value header as marqo search filter on home page search, so https://brians-pub.testingnear.me/?lat=39.8616981506&lon=-104.672996521&radius=20500 will show only events owned by the user ID associated with brians-pub subdomain. Compare to https://testingnear.me/?lat=39.8616981506&lon=-104.672996521&radius=20500 which should show 8 events
Introduces REST endpoints for search (TODO: need to parameterize the search call, params are still hardcoded at the time of this writing)
- {"/api/event", "POST", handlers.PostEventHandler, None},
- {"/api/events", "POST", handlers.PostBatchEventsHandler, None},
- {"/api/events", "GET", handlers.SearchEventsHandler, None},
- {"/api/events/{eventId}", "GET", handlers.PostEventHandler, None},
Fixes previously not-working latitude and longitude search (working now in Marqo db) compare the results on a radius, the radius param values here indicate there's a problem with the calculation math TODO: fix this
does not guarantee chronological sort order. Undecided as to whether we actually do this or decide it's unreasonable to ask of a vector DB, due to not being column / row oriented.