Allow for control of design token display in dropdown

Some CSS properties do not need to be seen by non technical members of a design team. There could be an option when registering a design token in the visual editor that lets you hide the display of the actual CSS value of a design token. For example,

Builder.register("editor.settings", { designTokens: { letterSpacing: [ { name: 'user friendly name', value: '-0.02em' , showValue: false }]}})

would make it so that -0.02em is not shown in the dropdown when selecting my user friendly name design token