reduce size of wasm package by making LSP and Rayon optional to get a small WASM runtime-only build

[yeus]

Current WASM target packages LSP and rayon dependencies which increase the size of the package to ~5Mb. We can reduce this to ~1Mb by optionally removing those dependencies using rust features. This make sit much more feasible to be included in projects as a pure modelica runtime.

[yeus]

this will probably also go along with a general cleanup of the wasm target.

• clean up options
• see, how we can incoporate the flags from .cargo/config.toml when rayon becomes optional.