[Lens] Keyboard-selected items should follow user traversal of drop zones

[MichaelMarcialis]

During a keyboard drag event in Lens, I'd love to see the field or dimension item being acted upon following the user's drop zone focus. I feel like seeing the field/item appearing in close proximity to its final drop location provides some valuable visual context and validation. Below is a quick visual of what I'm talking about here.

Also, when utilizing the left/right keys to move a keyboard-selected dimension item to a new dimension, the keyboard-selected dimension item continues to show in the origin dimension (ex. when moving a dimension item from "Vertical axis" to "Break down by"). In addition to the previous comment, I think it would be a helpful visual for users if a phantom space/blank was used in its original position in the origin dimension. I feel that would better indicate to users that this action will result in the dimension item being taken out of the originating dimension and taken elsewhere.

Originating issue: #51739
Enhancement to previous PR: #89745

[elasticmachine]

Pinging @elastic/kibana-app (Team:KibanaApp)