Closes#3027
Roamers: Get PID generated externally
NPokemon: Get PID from a fixed value
Forced (Anti)Shiny: Get PID altered
Thanks @LegoFigure11 && Princess Emily (discord 4650) !
EncounterTrade: don't init Location to -1; keep as default 0 and use that as the pivot for default met location. Move Fateful property to the sub-type that uses it (EncounterTrade4, for Ranch).
Move some EncounterStatic->PKM logic that is per-type to the associated type overloaded methods. Rearrange order of properties to be more consistent with interfaces
Gen3: Initialize some classes without using post-constructor setters. The `init` setter functionality coming in c#9 won't be usable as the net46 runtime/netstandard2 doesn't support it on current previews. Do it this way so we can explicity initialize some required properties rather than apply version on a second iteration.
Still some pending stuff like bad mystery gifts
gen2 static encounters on g/s applying met level and not location
gen6 ralts trade (no nickname) being flagged as nicknamed when it shouldn't
gen4 manaphy egg not having a hatch location (worked fine if you transferred it up)
gen3 antishiny gifts not setting their PIDs (jirachi WC3)
gen5 N's pkm gifts setting the wrong nature
gen3 unown not being generated correctly, cosplay pikachu being allowed form0, non-BugCatchingContest no longer require Sport ball, oras dexnav marill now uses the azurill eggmove table
