server/ui: support typed deployment parameters with dynamic forms

[plyr4]

Description

support a better process for creating deployments.

the idea is to have yaml keys that define how a dynamic form should render in the UI.

deployment:
  deployRegion
    inputs:
      region:
        type: string
        description: which fake region to deploy to
        default: east
      options:
        type: stringarray
        description: some list of string options
        default: [ foo, bar ]

Spinnaker screenshot for inspiration:

[JordanSussman]

You could also draw inspiration from GitHub issue forms for the YAML schema.