SNOW-3052213: Add support for the DEFAULT_PYTHON_ARTIFACT_REPOSITORY parameter

[sfc-gh-bkogan]

1. Which Jira issue is this PR addressing? Make sure that there is an accompanying issue to your PR.

   Fixes SNOW-3052213

2. Fill out the following pre-review checklist:

   • I am adding a new automated test(s) to verify correctness of my new code
     • If this test skips Local Testing mode, I'm requesting review from @snowflakedb/local-testing
   • I am adding new logging messages
   • I am adding a new telemetry message
   • I am adding new credentials
   • I am adding a new dependency
   • If this is a new feature/behavior, I'm adding the Local Testing parity changes.
   • I acknowledge that I have ensured my changes to be thread-safe. Follow the link for more information: Thread-safe Developer Guidelines
   • If adding any arguments to public Snowpark APIs or creating new public Snowpark APIs, I acknowledge that I have ensured my changes include AST support. Follow the link for more information: AST Support Guidelines

3. Please describe how your code solves the related issue.

   Reads the SYSTEM$GET_DEFAULT_PYTHON_ARTIFACT_REPOSITORY built in system function to determine the default artifact repository to use for function creation. SQL generation is unaffected, just have to change the places that assume artifact_repository is None means we are using conda.

   Some things to note:

• session._packages removed and merged with session._artifact_repository_packages. This is because we can no longer assume the default repo name, so we must tag each package with it's corresponding repo name.
• Added session._default_artifact_repository_cache to cache repeated invocations of getting the default repo in the same DB/schema context. The cache introduces a gap where users who manually alter the parameter value in same context will not see that value reflected if the cache is already set. This is a reasonable tradeoff for now, we can follow up if it becomes an issue.

[sfc-gh-bkogan]

Tests currently failing because the system function isn't available in the test environment yet. EDIT: should be good now