[feat] OAuth support (#307)

[andrefurlan-db]

Description

This PR adds support for OAuth: both 3-legged and 2-legged.

From a user perspective, token is not mandatory anymore. OAuth with SSO (browser login) will be used if auth_type: oauth is defined.

For automation and CI/CD use cases, client_id and client_secret are now available as config.

Usage

AWS

It just works as long as admin has enabled databricks-dbt-adapter as an OAuth application:

curl -n -X POST https://accounts.cloud.databricks.com/api/2.0/accounts/<Account ID>/oauth2/published-app-integrations -d '{ "app_id" : "databricks-dbt-adapter" }'

Profile:

  type: databricks
  host: "<your databricks host name>"
  http_path: "<http path for warehouse >"
  auth_type: "oauth"

Azure

A Public client/ Native Azure AD Application must be created with redirect URL http://localhost:8020. For SSO, Azure Application (client) ID must be used for client_id.
Profile:

  type: databricks
  host: "<your databricks host name>"
  http_path: "<http path for warehouse >"
  client_id: "<Azure AD Application ID>"
  auth_type: "oauth"

GCP

GCP is not supported at the moment.

Checklist

• 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
• I have updated the CHANGELOG.md and added information about my change to the "dbt-databricks next" section.

[susodapop]

LGTM with a small nit