enterprise/internal/insights: add basic store package + testing infrastructure
Created by: slimsag
This adds the basic store package implementation (just the groundowork, no actual implementation) based on what we do in campaigns, code monitoring, etc.
I am sending this as a separate PR before implementing the store, as it is a non-trivial amount of setup code which is nice to track separately for purposes of documentation and for seeing how we can improve adding backends like this, campaigns, code monitoring, etc. in the future.
Depends on: (TODO: send other PR for running timescale on CI)
Helps #17218
Fixes #17226
Signed-off-by: Stephen Gutekanst [email protected]