[WIP] Extract ads.auth into standalone oracle-ads-auth package

[mrDzurb]

Description:

This PR pulls our OCI-authentication logic (ads.auth) out of the main oracle-ads repository and into a brand-new, independently installable PyPI package called oracle-ads-auth. It’s the very first step in a broader effort to refactor the ADS monolith into a family of small, purpose-built components—so that users can choose to install only the pieces they need, reducing footprint and dependency bloat.

For new users:

pip install oracle-ads-auth
pip install oracle-ads

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What Changed

1. New Package:

   • Created oracle-ads-auth with its own pyproject.toml, README, and namespace package setup.

2. Namespace Packaging:

   • Added pkgutil.extend_path in ads/__init__.py of both repos to share the ads namespace seamlessly.
   • Updated [tool.setuptools.packages.find] in both pyproject.toml files so that import ads.auth works regardless of install order.

3. Backward Compatibility Shim:

   • Replaced ads/common/auth.py in the main repo with a thin forwarder that re-exports everything from ads.auth (in oracle-ads-auth).
   • Users of the old import paths (from ads.common.auth import default_signer, etc.) continue to work without change.

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Migration & Usage

• For new users:

  pip install oracle-ads-auth
  pip install oracle-ads

• Existing code using any of these will remain functional:

  from ads.common import auth
  creds = authutil.default_signer()
  
  # or
  import ads.auth
  ads.auth.set_auth(...)
  
  # or
  import ads
  ads.set_auth(...)

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Next Steps

• Add CI jobs to publish and version these sub-packages independently.
• Plan a deprecation timeline for legacy imports once downstream consumers have migrated.

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Reviewer notes:
This change introduces no functional regression and keeps all existing ADS APIs intact. Feedback welcome on the packaging strategy and compatibility shim!

[github-actions]

⚠️ This PR changed pyproject.toml file. ⚠️

• PR Creator must update 📃 THIRD_PARTY_LICENSES.txt, if any 📚 library added/removed in pyproject.toml.
• PR Approver must confirm 📃 THIRD_PARTY_LICENSES.txt updated, if any 📚 library added/removed in pyproject.toml.