Add support for Snowflake key-pair authentication

ecerulm

Currently the dataiku only support "User/Password" and "OAuth" for Snowflake connection.

Snowflake has Key-pair authentication https://docs.snowflake.com/en/user-guide/key-pair-auth, which I would like to use for my service accounts.

Jorge

We are looking also to have this sort of functionality. It would be great to have this implemented allowing for extra security of the data