feat: spine 4.0 plugin support

[epreston]

Add Spine 4.0 Plugin Support

• Add media and examples for Spine 4.0 runtime
• Update build system to create 4.0 plugin
• Add prebuilt plugin
• Update docs, minor tool adjustments

Fixes a gap in this support matrix.

I confirm I have read the contributing guidelines and signed the Contributor License Agreement.

[mvaligursky]

anything still needed on this one @epreston ?

[epreston]

It's a placeholder at the moment so we don't forget. I should put some effort into this one.

[epreston]

Should be sorted now in the new PR, ready for review.