add privateKey as a JVM property for Snowflake JDBC Connector

[parthshyara]

Description

• Adds support for the privateKey authentication property in the Snowflake connector.
• The Snowflake JDBC driver already supports this property, but Trino previously had no way to pass it through.
• With this change, users can configure key-pair authentication directly in the catalog instead of relying on file-based approaches.

Additional context and related issues

• Fixes Snowflake Connector: Add support for privateKey authentication property #26514
• Provides a more secure and convenient alternative to using JDBC URL parameters with file paths and passwords.
• Particularly useful for dynamic catalog creation, where file system dependencies are harder to manage.

Release notes

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## Snowflake connector
* Add support for the `privateKey` authentication property to enable key-pair authentication. (#26514)

[parthshyara]

Re-opening from #26519