Use Republic.jl to forward subpackage APIs

[AntonOresten]

I recently created Republic.jl to replace and extend Reexport.jl. After jumping the gun on v1 (which had questionable inheritance semantics) I'm now much more confident in v2, taking inspiration from the pre-1.11 @public machinery from #3058.

The previous code has special handling for GPUToolbox.jl's enums, so this PR relies on GPUToolbox switching to Republic.jl as well for pre-1.11 enum support.

This would be my first real stress-test of Republic, but I don't see any potential problems yet.

[maleadt]

Interesting! I'd be fine with depending on Republic.jl for this. Any reason you went with a new package, and not an extension to Reexport.jl? Especially seeing the s/@reexport/@republic reexport=true/.

[AntonOresten]

Reexport.jl has a very clear scope, and the public keyword introduces a different dimension — forwarding non-exported names, cross-version tracking, composing inheritance (implicit imports) with re-exporting. Bolting that onto Reexport felt like stretching it beyond its purpose. Also the name was too good to pass up.

There could definitely be @reexport -> @republic reexport=true for convenience though. I also think MurrellGroup/Republic.jl#9 is a missing piece for expressiveness.