Support external browser authentication for SSO

[msardana94]

Is your feature request related to a problem? Please describe.
We have Google SSO login for snowflake and as per security policies, we don't allow user/password to any developer. This makes local development difficult and current workaround is to use local postgres instance or csv as target which many times cause problems in pre-prod.

Describe the solution you'd like
Snowflake python connector supports externalbrowser authentication for scenarios such as SSO as mentioned here. Similar to dbt snowflake config for this use case, it will be great if target-snowflake config can also support this authentication method.

This is somewhat similar to another recent issue #312