Lock element to prevent moving it

[vincentfretin]

Add a lock icon in the hierarchy panel next to each element to prevent selecting an element via the viewport (in 3dstreet we added data-ignore-raycaster attribute for that behavior), and also forbid changing the transform via the UI (in 3dstreet we added the data-no-transform attribute for that)
Add a single data-inspector-locked attribute to the entity.
Note that it should not lock the children.
One use case of mine: lock a fridge to be able to move bottles inside it, currently you can't select a bottle inside the fridge via the viewport, you have to select a bottle from the hierarchy panel.