Pydantic for Test Scenario

[amaslenn]

Summary

Introduce Pydantic schema validation for Test Scenarios.

Test Plan

1. CI

Additional Notes

—

Highlights for Release notes

We are working on schema improvements to simplify configs management and make them verifiable. This will help ensure that configs are correct before expensive runs on real hardware. Today we are enabling it for Test Scenario configs. This is a continuation of #145.

1. Tests becomes and array. This helps making case names more expressive:
   before:

   [Tests.1]
   # ...

   now:

   [[Tests]]
   id = "any-name.you_want" # before it was just "1"

2. id field is mandatory and must be unique and is used to specify dependencies:

   [[Tests]]
   id = "Tests.1"
   # ...
   
   [[Tests]]
   id = "Tests.2"
   # ...
     [[Tests.dependencies]]
     id = "Tests.1"
     # ...

3. name (under the list of tests) renamed to test_name to better reflect its meaning. It still references a test defined in a separate TOML file.
4. Dependencies converted to a list to support multiple dependencies of the same type.
   before

   # ...
   
   [Tests.2]
   name = "ucc_test_alltoall"
     [Tests.2.dependencies]
     start_post_comp = { name = "Tests.1", time = 0 }  # only one dependency of this type is allowed

   now

   # ...
   
   [[Tests]]
   id = "Tests.3"
   test_name = "ucc_test_alltoall"
   # ...
     [[Tests.dependencies]]
     type = "start_post_comp"
     id = "Tests.1"
   
     [[Tests.dependencies]]
     type = "start_post_comp"
     id = "Tests.2"

[TaekyungHeo]

We should also have a corresponding PR in CloudAIX. The CloudAIX TOML files and code should be updated accordingly.

[srivatsankrishnan]

LGTM.