Add Partial Paris mulligan support

[Partial Paris Mulligan rule](https://www.mtgsalvation.com/forums/the-game/commander-edh/565962-official-edh-mulligan-rules-do-you-like-partial):

> Because Commander games are long and usually not played in multigame matches, the format uses a modified mulligan rule designed to alleviate mana-light hands without significantly increasing the odds of finding individual cards. This is also known as the "Brittany" mulligan rule.
>
> In turn order, players may exile (face down) some or all of the cards in their hand.
> Each player then draws one less card from their deck than the number they exiled.
> Players who exiled at least one card may return to step 1 and repeat the process, drawing one less card each time.
> Players shuffle all exiled cards into their deck.