Face down need improves/research (usage of instanceof MorphAbility)

From related fix in #11962 -- usages of all `instanceof MorphAbility` must be checked and replaced to support Disguise ability too (if required):


TODO:
1. [ ] `BecomesFaceDownCreatureAllEffect` like [[Ixidron]] -- must be researched/reworked, I don't touch it in #11873, so it can be buggy -- must use `makeFaceDownObject`;
2. [x] [[Exiled Doomsayer]] -- looks fine, works with morph only;
3. [x] `MorphSpellsCostReductionControllerEffect` - fixed by #11962;
4. [ ] `PlayerImpl` - must be research. ~~Looks like all face down abilities must be supported (not Morph only) in "can be cast as though it had flash"~~. Well, nope. It's about wrong always playable mark for non-playable card with morph ability (6e1da09023eea715e5572246bef0e6fec9d2dc76)

Start with the remaining `instanceof MorphAbility` usages named in the issue, especially `BecomesFaceDownCreatureAllEffect` and `PlayerImpl`, and review related fix #11962. Research whether these paths must support Disguise and whether `makeFaceDownObject` is required; done means the unchecked face-down behavior and incorrect playable marking are resolved.

Written by the indexing model from the issue text.