feat(udf): Improve registry secrets api

[daryllimyt]

Features

• Implement and use RegistrySecret in place of a list[str] for registry secrets
• Add SecretName and SecretKey patterns for runtime pattern validation
• Add docstrings with example usage

Impact

• ⁠Single source of truth for what secrets are required
• ⁠⁠Solves documentation: colocates it directly with the UDF, and is easier to automate updating docs
• ⁠⁠Declarative and obvious to the user
• ⁠⁠Better for validation as it’s all contained in the udf registry, no need to parse the actual funciton body to look for env vars
• Enforce secret name and key patterns

Screens