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

[Grath]

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.

[github-actions]

Ichorid - (Gatherer) (Scryfall) (EDHREC)

{3}{B}
Creature — Horror
3/1
Haste
At the beginning of the end step, sacrifice Ichorid.
At the beginning of your upkeep, if Ichorid is in your graveyard, you may exile a black creature card other than Ichorid from your graveyard. If you do, return Ichorid to the battlefield.

Masked Vandal - (Gatherer) (Scryfall) (EDHREC)

{1}{G}
Creature — Shapeshifter
1/3
Changeling (This card is every creature type.)
When Masked Vandal enters the battlefield, you may exile a creature card from your graveyard. If you do, exile target artifact or enchantment an opponent controls.

Immortal Coil - (Gatherer) (Scryfall) (EDHREC)

{2}{B}{B}
Artifact
{T}, Exile two cards from your graveyard: Draw a card.
If damage would be dealt to you, prevent that damage. Exile a card from your graveyard for each 1 damage prevented this way.
When there are no cards in your graveyard, you lose the game.