Sequential panner stabilization

[teresaqhoang]

Motivation and Context

This PR sets SequentialPlanner as the default for Chat Copilot and introduces some changes to help stabilize the experience, including:

• Giving the user the option to skip missing functions errors from the planner.
• Allow the user to retry on invalid plan errors (i.e., invalid JSON, plans returned in non-XML or just in natural language)
• Explicitly highlight points of failures in proposed plan to prompt user to fix before approving / denying

Description

webapi

Changes on behavior of below flags:

• AllowRetriesOnInvalidPlan:
  • If true, ExternalInformationSkill will return plan creation if LLM returns an invalid plan. Fixed invalid plan retry logic when PlanningException.ErrorCodes.InvalidPlan is thrown.
• SkipOnMissingFunctionsError: Whether to allow missing functions in the plan on creation then sanitize output. Functions are considered missing if they're not available in the planner's kernel's context.
  • If set to true, the plan will be created with missing functions as no-op steps that are filtered from the final proposed plan.
    - When plan returns, sanitize plan of functions not available in Planner's kernel. Merge context variables into plan parameters. Add flag $???. to indicate unknown variables in plan preview.
  • If this is set to false, the plan creation will fail if any functions are missing.

If plan contains function not available in planner's kernel's context, removed function is logged to console

webapp

• On view plan:

  • Add validation for plan step inputs when edits are allowed (if user approval is required).
  • Display an error message when inputs contain interpolated variables or fields marked $???.
  • Fix PlanStepInput component to include validation for plan step inputs when edits are allowed (if user approval is required) and to update form value on submit.
  • Fix PlanViewer component to include updated plan in message property and to update context variables on plan action.
  • Fix an issue where updating a chat message's content was not properly updating the message in the UI.

  Invalid Inputs
  

After valid edits

Sequential Plan

Contribution Checklist

• The code builds clean without any errors or warnings
• The PR follows the Contribution Guidelines and the pre-submission formatting script raises no violations
  - [ ] All unit tests pass, and I have added new tests where possible
• I didn't break anyone 😄