Refactor code in modules/displays and screensaver

[rohanpurohit]

This issue is split off from #359 comment

modules/display:

• Deciding for ourselves what belongs in modules/displays, and moving files in and out as needed: #359 (comment)
• Turning bannerType into an Enum: #359 (comment)
• Renaming the Data type internal to the MultiStepWizard to something more descriptive: #359 (comment)
• Replacing committedSetting with setValueActual, if possible: #359 (comment)
• Changing the toggleBetween field from an array of an unnamed object type to an array of ToggleSetting objects, where the ----ToggleSetting is defined as an interface with label and value fields: #359 (comment)
• Renaming ValueDisplay and ValueSelectorDisplay to something more descriptive/specific: #359 (comment) and #359 (comment)

moduels/screensaver:

• Rename "Control Wrapper" to something more descriptive.