Add multi-object editing support to link or unlink multiple colors at once

[SametHope]

Issue:
When attempting to link or unlink colors while selecting multiple objects, all selected objects visually appear to update, but in reality only one object is actually linked. It looks like multi-object editing is not currently supported.

Steps to reproduce:

1. Select multiple objects in the scene or hierarchy.
2. Attempt to link a color to all selected objects at once.
3. Observe that while all selected objects display the new color, only one object is truly linked to it.

Expected behavior:
All selected objects should be linked or unlinked to the chosen color simultaneously for consistent multi-object editing.

Actual behavior:
All selected objects visually change color as if they were linked, but only one object actually receives the link. This gives the misleading impression that multi-editing worked, while in fact it only linked a single object and simply changed the color of the others.

Proposal:
Add proper support for multi-object editing so that linking or unlinking a color applies to all currently selected objects if relevant.

[SametHope]

For more context, I am trying to mass-edit all my buttons in a scene to link their colors so I can manage their tints (Normal, Highlighted, Pressed, Selected, Disabled, etc.) from the Palette window.

Because of this issue, I have to manually link all colors one by one, which is really inconvenient.