[Experiment] Change experiment cli "--file" to "--template"

[lalala123123]

Description

1. Change experiment cli "--file" to "--template"
2. pf experiment start --template, create a new experiment

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.
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Testing Guidelines

• Pull request includes test coverage for the included changes.

[github-actions]

SDK CLI Global Config Test Result zhrua/update_experiment_cli

2 tests   2 ✅  50s ⏱️
1 suites  0 💤
1 files    0 ❌

Results for commit 3082037.

[github-actions]

promptflow-tracing unit test result zhrua/update_experiment_cli

 4 files   4 suites   22s ⏱️
 4 tests  4 ✅ 0 💤 0 ❌
16 runs  16 ✅ 0 💤 0 ❌

Results for commit 3082037.

[github-actions]

promptflow-tracing e2e test result zhrua/update_experiment_cli

 4 files   4 suites   1m 39s ⏱️
 8 tests  8 ✅ 0 💤 0 ❌
32 runs  32 ✅ 0 💤 0 ❌

Results for commit 3082037.

[github-actions]

promptflow SDK CLI Azure E2E Test Result zhrua/update_experiment_cli

  4 files    4 suites   3m 48s ⏱️
168 tests 149 ✅ 19 💤 0 ❌
672 runs  596 ✅ 76 💤 0 ❌

Results for commit 3082037.

[github-actions]

SDK CLI Test Result zhrua/update_experiment_cli

   12 files     12 suites   40m 33s ⏱️
  451 tests   433 ✅ 18 💤 0 ❌
1 804 runs  1 732 ✅ 72 💤 0 ❌

Results for commit 3082037.