Implemented the TreeViewSelector component for DDF

[skateman]

I did some cleanup in the TreeView codebase, we now have the following components:

• TreeViewBase - a component that renders a tree without using redux
• TreeViewRedux - a component that renders a tree with redux
• TreeViewField - a DDF component that uses TreeViewBase and exposes checkboxes
• TreeViewSelector - a DDF component that uses a TEXT_FIELD with a button addon that opens a Modal containing a tree where you can select a single entity

{
    component: 'tree-selector',
    name: 'foo',
    label: 'Foo',
    loadData: () => http.get('/tree/test'),
    lazyLoadData: node => http.get(`/tree/test?id=${node.attr.key}`),
    identifier: node => node.fqname,
}

Fixes #6841

[himdel]

Settings > Application Settings >> Access Control .. edit a role
with this PR, all the checkboxes in the Product Features tree are unchecked

[skateman]

Settings > Application Settings >> Access Control .. edit a role
with this PR, all the checkboxes in the Product Features tree are unchecked

Fixed...

[miq-bot]

Checked commits skateman/manageiq-ui-classic@740c62c~...a7e5c70 with ruby 2.6.3, rubocop 0.69.0, haml-lint 0.28.0, and yamllint
1 file checked, 1 offense detected

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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.