FLUX XLabs IP-Adapter Support

[RyanJDick]

Summary

This PR adds support for the XLabs IP-Adapter (https://huggingface.co/XLabs-AI/flux-ip-adapter) in workflows. Linear UI integration is coming in a follow-up PR. The XLabs IP-Adapter can be installed in the Starter Models tab.

Usage tips:

• Use a cfg_scale value of 2.0 to 4.0
• Start with an IP-Adatper weight of ~0.6 and adjust from there.
• Set cfg_scale_start_step = 1
• Set cfg_scale_end_step to roughly the halfway point (it's unnecessary to apply CFG to all steps, and this will improve processing time).

Sample workflow:

Result:

Related Issues / Discussions

Prerequisite: #7152

Remaining TODO:

• Update default workflows.

QA Instructions

• Test basic happy path
• Test with multiple IP-Adapters (it runs, but results aren't great)
• Test with multiple images to a single IP-Adapter (this is not supported for now)
• Test automatic runtime installation of CLIP-L, CLIP-H, and CLIP-G image encoder models if they are not already installed.
• Test starter model installation of the XLabs FLUX IP-Adapter
• Test SD and SDXL IP-Adapters for regression.
• Check peak memory utilization.

Merge Plan

• Merge FLUX CFG support #7152
• Change target branch to main

Checklist

• The PR has a short but descriptive title, suitable for a changelog
• Tests added / updated (if applicable)
• Documentation added / updated (if applicable)