After this change, `mini_table` only has MiniTable definitions themselves. Everything having to do with the MiniDescriptor wire format is in `mini_descriptor`.
Also rearranged some of the files in mini_table to have better structure for `internal/`.
This CL contains no functional change.
PiperOrigin-RevId: 543529112
There are several other functions which might eventually end up here and ideally become unified across json/ and text/ and io/ so this is just a first step to create the new subdir and get rid of upb/internal/
PiperOrigin-RevId: 488954926
Lots of changes but it's all just moving things around.
Backward-compatible stub #include's have been provided for now.
upb_Arena/upb_Status have been split out from upb/upb.?
upb_Array/upb_Map/upb_MessageValue have been split out from upb/collections.?
upb_ExtensionRegistry has been split out from upb/msg.?
upb/decode_internal.h is now upb/internal/decode.h
upb/mini_table_accessors_internal.h is now upb/internal/mini_table_accessors.h
upb/table_internal.h is now upb/internal/table.h
upb/upb_internal.h is now upb/internal/upb.h
PiperOrigin-RevId: 456297617