Add adapter telemetry method for core model run snowplow event.

[VersusFacit]

resolves #301
docs dbt-labs/docs.getdbt.com/#

Problem

We need a way to expose adapter telemetry for our internal product adoption analytics.

Solution

The base adapter provides a simple method which is used in dbt core and its tracking system. This method will be overwritten for each adapter that we wish to collect telemetry for.

Checklist

• I have read the contributing guide and understand what's expected of me
• I have run this code in development, and it appears to resolve the stated issue
• This PR includes tests, or tests are not required/relevant for this PR
• 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

[github-actions]

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[VersusFacit]

Proof of operation for fallback method (i.e. adapter does not override)

Note adapter_details is {}. It'll be non-empty in, say, snowflake (here) which provides an override with snowflake-specific info. This field is optional in our JSON schema.

[colin-rogers-dbt]

Is this unit test-able?