Update GitHub templates and markdown files.

Update GitHub templates and markdown files.

- Issue templates are replaced with forms.  Forms allow to explicitly ask
  for certain info before an issue is opened, they can be programmatically
  queried via GH actions to get the data in fields.

- Added language around GH discussions vs the forum in the issue forms.

- Added GH discussions templates.  These templates delineate which types
  of discussions belong on GitHub vs the community forum.

- Created SUPPORT.md to delineate which types of topics belong on GitHub
  vs different support channels (community forum/docs/commercial support).

- Updated CONTRIBUTING.md:
  - Removed text that belongs in SUPPORT.md.
  - Added F5 CLA clarifying text.

- Added badges to README.md.  Most of these are there to make information
  even clearer, moreso for users reading README.md from sources outside
  GitHub.