Update flux_redux.py with downsampling and weight options

[skunkworxdark]

Add downsampling and weight to Redux node - This should allow the main prompt conditioning to gain some traction over a Redux conditioning.

Summary

The downsampling and weight idea is derived from https://github.com/kaibioinfo/ComfyUI_AdvancedRefluxControl

• Downsampling of 3-4 is where the main prompt starts to gain some traction.
• Weight of 0.3-0.4 is where it weakens the redux conditioning enough for the main prompt to have an effect.

Downsampling reduces the size of the redux conditioning
Weight reduces the intensity of the conditioning but not the size

Related Issues / Discussions

N/A

QA Instructions

Test defaults to work like the previous non-down-sampled redux

https://stable-diffusion-art.com/flux-redux/ - article on the original comfy node.

Merge Plan

Needs testing and reviewing and frontend consideration discussed

Checklist

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

[skunkworxdark]

@hipsterusername - here is the redux node changes. as discussed.

[psychedelicious]

• Fixed a small issue in the node where an and should have been an or.
• Added support to Canvas via new Image Influence setting for FLUX Redux. This mirrors the comfy node's UI. The mapping of influence settings to node parameters is done in invokeai/frontend/web/src/features/nodes/util/graph/generation/addFLUXRedux.ts. It's straightforward to edit that mapping to fine-tune image influence setting. For now, it matches the comfy node.