Make the Flavor form fully API driven and functional

[skateman]

Even though the flavor form has been converted to react, it was still using controller routes from the ui-classic repo to feed some data into its dropdowns. As these endpoints have matching endpoints in the API, the form has been be converted to use them instead.

Found a bug in DDF that can be triggered from here: data-driven-forms/react-forms#866

Depends on:
ManageIQ/manageiq#20747
ManageIQ/manageiq-providers-openstack#659

[miq-bot]

Checked commit skateman@4db7336 with ruby 2.6.3, rubocop 0.82.0, haml-lint 0.35.0, and yamllint
1 file checked, 1 offense detected

**

• 💣 💥 🔥 🚒 - Linter/Haml - Linter::Haml STDERR:

warning: parser/current is loading parser/ruby26, which recognizes
warning: 2.6.6-compliant syntax, but you are running 2.6.3.
warning: please see https://github.com/whitequark/parser#compatibility-with-ruby-mri.