Selection count

Using PluginSelection to pass the current selection in Figma from the UI to the plugin code

• Changed the signature of PluginSelection from string[] to FrameNode[] and ComponentNode[] respectively
• Using the getters in Vuex to get the values of the selected frames and components in the store
• Adding back mock-local-storage because without it gitlab/ui doesn't work. It looks like gitlab/ui tries to do something with localstorage on startup but since Figma doesn't have local storage it crashes and nothing appears in the UI.

Error image