Consistently format WRAM values

[Rangi42]

macros/wram.asm uses db for one-byte values (like box_struct Species) and dw for two-byte values (like box_struct HPExp), leaving ds for larger values (like ds 3 for box_struct Exp) and free space. Meanwhile, wram.asm never uses dw and only uses db for wWaterRate and wWaterMons.

It could also use more UNIONs for overlapping values (like $60-byte wMonPartySpritesSavedOAM, $40-byte wTrainerCardBlkPacket, and many subsequent single bytes).