Add flow test http api

[YingChen1996]

Description

• run pf flow test --flow tests/test_configs/flows/web_classification --ui will start pfs if it's not stared and redirect to page like below (add a min js placeholder), we will encode flow path and pass it to ux for now and ux need use it as query parameter to call pfs flow api.
  URL: http://127.0.0.1:55057/v1.0/ui/chat?flow=QzpcVXNlcnNcY2hlbnlpblxyZXBvXHByb21wdGZsb3dcc3JjXHByb21wdGZsb3dcdGVzdHNcdGVzdF9jb25maWdzXGZsb3dzXHdlYl9jbGFzc2lmaWNhdGlvbg%3D%3D
  

• flow test
  

• experiment test
  

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Testing Guidelines

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[github-actions]

SDK CLI Global Config Test Result chenyin/add_pfs_api

3 tests   3 ✅  44s ⏱️
1 suites  0 💤
1 files    0 ❌

Results for commit ef73930.

♻️ This comment has been updated with latest results.

[github-actions]

promptflow SDK CLI Azure E2E Test Result chenyin/add_pfs_api

  4 files    4 suites   4m 49s ⏱️
186 tests 166 ✅ 20 💤 0 ❌
744 runs  664 ✅ 80 💤 0 ❌

Results for commit ef73930.

♻️ This comment has been updated with latest results.

[github-actions]

SDK CLI Test Result chenyin/add_pfs_api

   12 files     12 suites   44m 57s ⏱️
  488 tests   471 ✅ 17 💤 0 ❌
1 952 runs  1 884 ✅ 68 💤 0 ❌

Results for commit ef73930.

♻️ This comment has been updated with latest results.