Remove support for Array literals

Similar to the removal of Map literal support, this is aimed at simplifying the syntax and making it more consistent. Arrays are now created using Array.new, which takes every value as a separate argument:

Array.new(10, 20, 30, ...)

To make this more pleasant to work with, the methods StringBuffer.new and ByteArray.new now take a rest argument. This means you don't have to write ByteArray.new(Array.new(...)), and instead can write ByteArray.new(...). For the StringBuffer type this requires that we manually create an instance of it. To remove the need for using VM instructions directly, we introduce Object.allocate as a wrapper around this. This allows one to manually create instances like so:

static def some_method {
  let instance = allocate

  instance.init(...)

  instance
}