Infrastructure Mapping Wizard / Step 2

[serenamarie125]

Implement the second step of the Infrastructure Mapping Wizard.

Check with @priley86 on what he's done in the past with a dual pane type selector. We will not be contributing anything to PF for the dual pane selector for now, because of time constraints.

For Step 2, the user selects 1 or more Source Clusters, and a single Target Cluster, and then hits Add Mapping. The Add Mapping button should be disabled until those conditions exist. Upon hitting add mapping, the target cluster should be added as a parent, with the source clusters as children.

Note that Steps 2, 3 & 4 of this wizard will use very similar widgets.

Associated issues to be completed AFTER this issue :
#27 Infrastructure Mapping Wizard / Step 3
#28 Infrastructure Mapping Wizard / Step 4

[priley86]

@michaelkro would you mind taking a look at this? I think I shared my existing dual pane code with you, but let me know if you have any questions.

[michaelkro]

Closed by https://github.com/priley86/miq_v2v_ui_plugin/pull/44