Generate components/params.libsonnet file

The purpose of this file is to allow re-parameterization of components
after they are created.

`components/params.libsonnet` is generated on `ks init`. This file will
contain a jsonnet obj containing two objs:

1. global: contains user-defined global parameters; accessible to all
component and environments.
2. components: contains component-level parameters, defined initially
from `ks prototype use ...`

These objs are empty by default.