Expanded proposal template

• Solidified "graduated" requirements by tying it back to Big Bang's package integration guide
• Expanded proposal template with the following:
  • Version (bbtoc/v1alpha)
  • added vendor, license and quickstart to capture more info about the product
  • changed problemStatement to purpose to align with process requirements
  • changed initialMembers to contacts
  • added spec.pacakges[] to capture multiple packages in single project (e.g. Elasticsearch and ECK operator)
    • moved repoUrl to spec.packages[].repository
  • added spec.packages[].support to capture support team and level of commitment for incubating requirements
  • added spec.packages[].images to capture Iron Bank approval requests and grants for incubating/graduated requirements
  • added spec.packages[].pipeline to verify pipeline for graduated requirement
  • added spec.packages[].documentation to link required documentation per requirements
  • added spec.users to identify active or production users per incubating / graduated requirements
  • added spec.sign-offs for non-trivial validation / sign-off of requirements

Impact to current proposals should be minimal (a few key/value changes). Once merged, I can take a follow on action to update monitoring.yaml and opagatekeeper.yaml in sandbox to the new template.