AIP #61 v5: Analytics multi-chain support

[elpiel]

✔️ analytics route (GET /v5/analytics) #496

The analytics route should support multi-chains and filter out the record accordingly to the Chain extracted from sentry's authentication.

✔️ test_harness #511

The main test cases in test_harness are now complete but we are still missing tests regarding the analytics statistics.

Add tests to validate that statistics are recorded correctly for each channel and for all.