Implement ksonnet prototype

[hausdorff]

The ksonnet prototype command is specified in the ksonnet.next design doc from August 2017.

Implementing this specification implies the following work items:

• (@hausdorff) Update help documentation.
• Implement ksonnet prototype use. This involves:
  • (@jessicayuen) [If Jsonnet] expand it to the LSP-spec-compliant snippet JSON
    • (PR Support import param rewrite for jsonnet snippets #109) Implement Jsonnet AST -> string code emission.
    • (PR Support import param rewrite for jsonnet snippets #109) Implement import param rewriter in kubecfg codebase.
  • (@hausdorff) Expand the snippet (i.e., substitute in the variables from the CLI) and output to stdout.
    • Write snippet parser.
    • Write code to expand snippet templates
  • Wire up to the use command.
• (@hausdorff) Implement ksonnet prototype describe. This roughly involves:
  • Retrieving the documentation from the prototype file.
  • Render to stdout.

Future work:

• Implement ksonnet prototype search.