technical debt: renaming to limit use of the term 'metadata'

[dogversioning]

we now have too many things that are being referred to as metadata, and it is making things a bit fussy to message/manage, so we should do some light renaming.

items to touch:

• read/write metadata -> read/write s3_json
• site metadata -> data packaging status?
• bucket names should not contain meta
• study medata :might: be ok.

Once this is done, there may be some redundancies in shared functions that can be trimmed out - perhaps one central 'write json to s3' function anything can use?