Make the promptflow-azure an optional dependency; fix artifact logging.

[nick863]

Description

• Make promptflow-azure as an optional dependency
• Fix the mlflow-like artifact logging so that it shows in the UI.

All Promptflow Contribution checklist:

• The pull request does not introduce [breaking changes].
• CHANGELOG is updated for new features, bug fixes or other significant changes.
• I have read the contribution guidelines.
• Create an issue and link to the pull request to get dedicated review from promptflow team. Learn more: suggested workflow.

General Guidelines and Best Practices

• Title of the pull request is clear and informative.
• There are a small number of commits, each of which have an informative message. This means that previously merged commits do not appear in the history of the PR. For more information on cleaning up the commits in your PR, see this page.

Testing Guidelines

• Pull request includes test coverage for the included changes.

[github-actions]

promptflow-evals test result

  9 files  ±0    9 suites  ±0   2h 3m 5s ⏱️ - 6m 38s
 52 tests ±0   47 ✅ ±0   5 💤 ±0  0 ❌ ±0 
468 runs  ±0  423 ✅ ±0  45 💤 ±0  0 ❌ ±0 

Results for commit 7b64958. ± Comparison against base commit e0a7815.

♻️ This comment has been updated with latest results.