fix: add connection testing params for snowflake

[villebro]

CATEGORY

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• Bug Fix
• Enhancement (new features, refinement)
• Refactor
• Add tests
• Build / Development Environment
• Documentation

SUMMARY

When connecting to a Snowflake database, the "Test Connection" button reports "Seems OK!", even if the user does not have proper rights to access the relevant database, schema, role or warehouse. This is problematic, because the connector introduces irregular behavior if proper authorization is missing, for instance returning duplicated schema names during calls to inspector.get_schema_names(). This PR introduces a method BaseEngineSpec.mutate_db_for_connection_test which can be overridden by a db spec to introduce connection validation, and implements the mostly undocumented validate_default_parameters flag (disabled by default, probably due to performance reasons) for Snowflake that validates the connection params when pressing "Test Connection".

BEFORE

AFTER

TEST PLAN

ADDITIONAL INFORMATION

• Has associated issue:
• Changes UI
• Requires DB Migration.
• Confirm DB Migration upgrade and downgrade tested.
• Introduces new feature or API
• Removes existing feature or API

REVIEWERS

[willbarrett]

👍