Moving popsicle to yup !

[kunitoki]

It's Alive !

This PR migrates the entirety of Popsicle from its previous standalone JUCE integration into Yup as a first-class module.

Why this change? The decision to pull Popsicle into Yup was driven by practical and strategic considerations:

🐢 Slow upstream response from JUCE team
Despite Popsicle’s relevance, progress and discussions around its required changes in the JUCE framework have been sluggish to non existent. Essential updates and refinements were ignored, resulting in a bottleneck for any advancement in Popsicle.

🛠 Need for complete control
By bringing Popsicle into Yup, we eliminate the need to wait for upstream maintainers to respond or act. This gives us:

• Full ownership over Popsicle’s evolution.
• Freedom to make API and implementation changes rapidly.
• Ability to address bugs and feature requests without external dependencies.

🚀 Alignment with Yup’s philosophy
Yup is designed to be a forward-thinking, developer-centric framework. Popsicle’s inclusion fits perfectly with this ethos by providing native capabilities for scenarios that JUCE doesn’t prioritize.

🔄 What changed?

• Integrated Popsicle source files into the Yup tree under modules/yup_python.
• Updated build system to treat Popsicle as an internal module.
• Removed JUCE-specific wrappers that are no longer needed.
• Refactored a few APIs to better align with Yup’s coding standards and conventions.
• Setup infrastructure to build yup wheels, which will be the new popsicle.