Spike: Determine if we should fork Vue.Draggable

We haven't supported multi-drag and drop on boards due to the feature not being supported in Vue.Draggable. The plugin is available in the dependency (Sortable) it just has not been integrated into Vue.Draggable: https://github.com/SortableJS/Vue.Draggable/issues/649.

Let's use this spike to determine the risk in forking Vue.Draggable. Mainly want to see what dependencies we'll have to worry about this by having our own version (https://gitlab.com/gitlab-org/plan/-/issues/655#note_1027497791).

The new version of boards uses Draggable to drag and drop an issue.

Once Draggable supports multi drag (https://github.com/SortableJS/Vue.Draggable/pull/1052), it should be added to GraphQL boards.

Other possible solution to investigate: https://www.npmjs.com/package/vuedraggable-multi

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We will place the multi select behind a feature flag until this issue is resolved: !61955 (merged)