Log unauthenticated API submissions

Description

Accept unauthenticated POSTs to /log.

Accepts the following fields:

log_level: string/enum - restricted to python log level strings
event: string - limit length of event + data
data: dict[optional] - limit length of event + data

The following should be logged in addition to provided fields.

labels.log_type: string - always "remote"
labels.authenticated: bool - always false for now
trace_id - GCP reported value for API request (so API can be linked to front end request)
severity: log_level from request
remote_reported_event: as per request event
remote_reported_data: as per request data

Acceptance criteria

• payload is limited to maximum accepted URLs length + agent length + headers etc. I.e. the maximum GCP balancer would log, thus limiting the log costs to 2x that of what GCP does already.
• uses ucam-observe to log to GCP
• uses fast api bootstrap
• container with single endpoint + health endpoint