Move stdlib files somewhere else

[arnaudroques]

Right now, files are under root. And this is hard coded in Java/JS here

I suggest that me make this configurable by adding an argument in the main() function during init

Some we change this line into something like

await cheerpjRunMain("net.sourceforge.plantuml.wasm.RunEmpty",${cheerpjPath}/plantuml-wasm.jar, "/app/plantuml-wasm/stdlib/")

This way, this will be more flexible.

[arnaudroques]

This is implemented in last commit. The jar file has also been slightly reduced.

[sakirtemel]

Moved everything under plantuml-wasm, right now it's more compact: https://github.com/plantuml/plantuml-wasm/tree/main/plantuml-wasm