support both yaml and yml postfix

[Stephen1993]

Description

Please add an informative description that covers that changes made by the pull request and link all relevant issues.

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-core test result

0 tests   0 ✅  0s ⏱️
0 suites  0 💤
0 files    0 ❌

Results for commit ccd72b4.

♻️ This comment has been updated with latest results.

[github-actions]

SDK CLI Global Config Test Result chenyzhang/support_yaml_and_yml

3 tests   3 ✅  1m 8s ⏱️
1 suites  0 💤
1 files    0 ❌

Results for commit ccd72b4.

♻️ This comment has been updated with latest results.

[github-actions]

promptflow SDK CLI Azure E2E Test Result chenyzhang/support_yaml_and_yml

  4 files    4 suites   4m 43s ⏱️
213 tests 193 ✅ 20 💤 0 ❌
852 runs  772 ✅ 80 💤 0 ❌

Results for commit ccd72b4.

♻️ This comment has been updated with latest results.

[github-actions]

Executor Unit Test Result chenyzhang/support_yaml_and_yml

778 tests   778 ✅  3m 40s ⏱️
  1 suites    0 💤
  1 files      0 ❌

Results for commit ccd72b4.

♻️ This comment has been updated with latest results.

[github-actions]

Executor E2E Test Result chenyzhang/support_yaml_and_yml

238 tests   235 ✅  6m 47s ⏱️
  1 suites    2 💤
  1 files      1 ❌

For more details on these failures, see this check.

Results for commit ccd72b4.

♻️ This comment has been updated with latest results.

[github-actions]

SDK CLI Test Result chenyzhang/support_yaml_and_yml

    4 files      4 suites   45m 49s ⏱️
  578 tests   557 ✅ 21 💤 0 ❌
2 312 runs  2 228 ✅ 84 💤 0 ❌

Results for commit ccd72b4.

♻️ This comment has been updated with latest results.