Remove array.h and map.h as hdrs from :collections_internal
Remove alloc.h and arena.h as hdrs from :mem_internal (and add them to :mem)
Remove common.h and decode.h and encode.h as hdrs from :wire_internal
Lock down the visibility of :wire_internal to upb-only
Merge :mini_descriptor_encode_internal into :mini_descriptor_internal
PiperOrigin-RevId: 558235138