Refactor ExileFromGraveCost to only create a unique exile zone when actually necessary

Several cards have been noted as creating unique exile zones for cards they exile, when there are no linked abilities which rely on later access to those exiled cards:
[[Ichorid]]
[[Masked Vandal]]
[[Immortal Coil]]

All three of these cards use ExileFromGraveCost. This cost should be refactored to have a flag which determines whether or not to create a unique exile zone, rather than just always creating a unique exile zone, so that when it is used for cards without linked abilities to the exiled card the cards just go to the standard exile zone.

Start by locating ExileFromGraveCost and its uses in Ichorid, Masked Vandal, and Immortal Coil. Trace how it creates exile zones and determine where linked abilities require a unique zone. Done means those three cards use the standard exile zone while cases needing later linked access retain unique-zone behavior.

Written by the indexing model from the issue text.