Store function invocation records in time series database

[kars7e]

We need to record function invocations and their results. The nature of the data means that it isn't suitable for the entity store, and would probably be better stored in a time series database like influxdb. This feature should go hand-in-hand with exposing the function invocation data (results/logs) via API and consumed by the UI.

[berndtj]

A stop-gap could be that the invocation data has a TTL and that it is expired in order to address unbounded growth