Add basic UI for multiple PluginLinkedList

[med1844]

Phase 1

• [x] Create one band for each pluginLinkedList (BandComponent) and horizontally stack them
• [x] Create PluginWrapperComponent to hold plugin editors and serve as a conceptual wrapper that can be stored in BandComponent
• [x] For minimal functioning test, create PluginWrapperComponent for each of the currently hard coded plugins and display them

Phase 2

• [x] Add open editor button in PluginWrapperComponent.
  • [x] Take care of the window creation & closing, as well as VST editor instance storage (do we need this?)
• [x] Add append plugin button and corresponding callback function for selecting from scanned plugin list & create PluginWrapperComponent & append at corresponding BandComponent

[med1844]

Bands can now be normally created and horizontally stacked. See bd5c69ed9e499adb25c732454559633853132814.

[med1844]

ef2ea8d57e5153770cf113c934ae4fa4ecf65815: PluginWrapperComponent can be created & draw now.

[med1844]

82b66f0cb556b920c32cd8dc8bae382d29f57015: PluginWrapperComponent can now be created according to the given PluginLinkedList and correctly display their names.

[med1844]

• aebf4973fed5ee763c487de40b0ef21a7173123c: edit button added using the PluginWindow implementation from juce's AudioPluginHost project. This allows us to create separate TopLevelWindows, set titles, correctly close windows, create generic editor for plugins with no editors, etc.
• 77441d01a0e6af936d69e0d33ec49210f281ff8e: addPluginButton properly added & tested.