[FEATURE] Ml-commons plugin introducing a new optional field "config" in MLTooSpec

[jngz-es]

Is your feature request related to a problem?

Ml-commons is introducing a new field config in MLToolSpec as showed in the pr opensearch-project/ml-commons#2977. With the change, we allow cx to configure some static parameters for tools that stay unchanged/persist during the tool execution. It will fix a couple of bugs mentioned in the pr.

What solution would you like?

The pr opensearch-project/ml-commons#2977.

What alternatives have you considered?

N/A.

Do you have any additional context?

It's an optional field.

[dbwiddis]

This should be a simple change to the ToolStep class adding the new optional parameter.

• please also update the test case
• please also migrate the input/output set per [REFACTOR] Eliminate duplication of required input / output List/Set #535