Feature implement an Snowflake Schema importer in `datacontract import` cli

[dmaresma]

Please introduce a new import feature passing snwoflake account and creds to dump a Snowflake DatabaseName.SchemaName into odcs.yaml file
as datacontract import --format snowflake --source bestworkplaceonearth.canada-central.azure.snowflakecomputing.com --output odcs.yaml

using external browser authentication on the top of existing test/ SODA

Soda parameter | Environment Variable
-- | --
username | DATACONTRACT_SNOWFLAKE_USERNAME
password | DATACONTRACT_SNOWFLAKE_PASSWORD
warehouse | DATACONTRACT_SNOWFLAKE_WAREHOUSE
role | DATACONTRACT_SNOWFLAKE_ROLE
connection_timeout | DATACONTRACT_SNOWFLAKE_CONNECTION_TIMEOUT