Add adapter telemetry to snowplow event.

[VersusFacit]

Resolves https://github.com/dbt-labs/dbt-adapters/issues/301

Solution

We propose exposing a method on the base adapter that will use existing snowplow infrastructure for tracking user statistics for any adapter.

We designed the json schema and event data to make it easy for us to add additional per-adapter information as use-cases emerge.

Checklist

• [x] I have read the contributing guide and understand what's expected of me.
• [x] I have run this code in development, and it appears to resolve the stated issue.
• [x] This PR includes tests, or tests are not required or relevant for this PR.
• [x] This PR has no interface changes (e.g., macros, CLI, logs, JSON artifacts, config files, adapter interface, etc.) or this PR has already received feedback and approval from Product or DX.
• [x] This PR includes type annotations for new and modified functions.