YAML Stream Output

[olivierlemasle]

To get parity with C++/Go implementations, it would be great to implement YAML Stream Output.

Example with:

// yaml_stream.jsonnet
local
  a = {
    x: 1,
    y: b.y,
  },
  b = {
    x: a.x,
    y: 2,
  };

[a, b]

jsonnet -y yaml_stream.jsonnet 
---
{
   "x": 1,
   "y": 2
}
---
{
   "x": 1,
   "y": 2
}
...