Add Precise Reference to SDXL Starter Models

[hipsterusername]

Summary

This pull request introducesip_adapter_plus_sdxl, to the OSS Starter Models. The changes include documentation updates, model definition, and integration into relevant model bundles.

New Model Addition:

• Documentation Update: Added a link to the new ip_adapter_plus_sdxl model in the IP-Adapters section of the README.md file.
• Model Definition: Defined the new ip_adapter_plus_sdxl model in the StarterModel class, specifying its name, base model type, source, description, type, dependencies, and previous names.

Integration into Model Bundles:

• Model Bundles Update: Integrated ip_adapter_plus_sdxl into two model bundles in starter_models.py to ensure its availability alongside other models. [1] [2]

Related Issues / Discussions

Reports of people finding it confusing to find the SDXL Precise Reference model

QA Instructions

N/A

Merge Plan

Ready

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)