Feature/http odbc conn extra

[jpoley]

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

Problem

with existing http method for spark connections we are unable to pass custom odbc properties such as username / password instead of token and two way tls options.

Solution

provide an additional parameter called connection_str_extra allowing users to provide custom odbc connection properties.

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/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

[colin-rogers-dbt]

This is a great start, will follow up in #1093 to get it over the line