Sharing multiple block stacks (via Share the Love) results overlapping stacks

[carljbowman]

Expected Behavior

Stacks shared via Share the Love should not become stacked over one another. Rather than defaulting to the upper left corner of the workspace, stacks should be dynamically placed on the workspace relative to the other blocks on the workspace.

Actual Behavior

Blocks default to the upper left corner. This results in blocks overlapping, which is potentially confusing as stacks can appear to be hidden.

Steps to Reproduce

1. Create two (or more) stacks of blocks on the workspace
2. Create a second sprite
3. Drag stacks ("share the love") from the sprite from step 1 on the second sprite from step 2
4. Look at the blocks on the workspace of the second sprite, the recently dragged over block stacks should all be in the upper left corner on top of one another.

[towerofnix]

Note work on this can't be done until scratchfoundation/scratch-gui#4542 is reviewed/merged.