Implement Varargs Parameters support

[NotJustAnna]

com.github.adriantodt.lin.vm.impl.FunctionSetupLayer#step(FunctionSetupLayer.kt:40):

Implementation Notes:

• There must be atmost 1 varargs parameters.
  • This should be done at grammar/parser-level ¹, but enforced at compiler & VM level ².
• The parameters NEED to be handled/loaded in a left-to-right order, even with varargs.

Footnotes

1. See FunctionParser should disallow more than one varargs parameter. Lin#5 ↩

2. See Modify bytecode to allow atmost 1 varargs parameter in a function. Lin#6 ↩