Added If node and ability to link an Any output to a node input if cardinality matches

[JPPhoto]

Summary

This PR includes a feature + bugfix for the new If invocation and its editor interoperability:

• Added a new If invocation node (if) with:
  • input condition: bool
  • input true_input: Optional[Any]
  • input false_input: Optional[Any>
  • output value: Optional[Any] (with default=None to avoid persisted-session validation failures when omitted).
• Fixed frontend node-connection validation so AnyField can be used as a source where cardinality is compatible (instead of being blocked), which allows If.value to connect to typed inputs in the UI.
• Added/updated tests for:
  • If true/false behavior and graph connectivity
  • deserialization of if_output when value is missing
  • AnyField source compatibility and cardinality guardrails in UI connection typing.

Why:

• Enable practical conditional branching in workflows.
• Ensure the UI allows intended If output wiring.
• Prevent session reload crashes caused by missing if_output.value in persisted JSON.

How:

• Implemented the invocation in backend Python.
• Updated frontend type compatibility logic.
• Added focused regression tests on both backend and frontend paths.

Related Issues / Discussions

QA Instructions

1. Backend schema/output checks

   • Verify IfInvocationOutput.value is optional with default None.
   • Verify deserialization test exists and passes in a full dev environment.

2. UI connection behavior checks

   • Create a graph with If node and connect If.value to a typed input (e.g. string input).
   • Confirm connection is accepted for compatible cardinalities, and rejected for incompatible ones (e.g. SINGLE -> COLLECTION).

3. Automated tests

Merge Plan

Checklist

• The PR has a short but descriptive title, suitable for a changelog
• Tests added / updated (if applicable)
• ❗Changes to a redux slice have a corresponding migration
• Documentation added / updated (if applicable)
• Updated What's New copy (if doing a release after this PR)