feat: stack plugin

[awesthouse]

What does this pull request change?

Add StackPlugin to dm-core-plugins. Allows user to stack views on top or next to each other.
In items array, just pass viewConfig objects

Example of config:

{
      "name": "Dashboard",
      "type": "CORE:UiRecipe",
      "description": "ESS Plot",
      "plugin": "@development-framework/dm-core-plugins/stack",
      "config": {
        "type": "PLUGINS:dm-core-plugins/stack/StackPluginConfig",
        "items": [
          {
            "type": "CORE:ReferenceViewConfig",
            "scope": "sce",
            "recipe": "Date"
          },
          {
            "type": "CORE:ReferenceViewConfig",
            "scope": "job",
            "recipe": "Fetch_Signals_OmniaTS"
          },
          {
            "type": "CORE:ReferenceViewConfig",
            "scope": "sce.signals",
            "recipe": "List"
          }
        ]
      }
    },

Open to discussing naming. "MultiView" to me seems like you can switch between multiple views of the same content. "Flexbox" is more css language. If we describe this as user being able to stack views on top of or next to each other - I feel like it's pretty self-explanatory.

Why is this pull request needed?

Help with some layout use-cases that are a bit over-complicated.

Issues related to this change

#1258

[pbullhove]

LGTM