For POST on RPC, allows:
* passing a json object without using `Prefer: params=single-object`
The function must be defined with a single unnamed json param and
`Content-Type: application/json` must be specified.
* uploading binary to a function
The function must be defined with a single unnamed bytea param and
`Content-Type: application/octet-stream` must be specified.
* uploading raw text to a function
The function must be defined with a single unnamed text param and
`Content-Type: text/plain` must be specified.
BREAKING CHANGE If there's a function "my_func" having a single
unnamed json param and other overloaded pairs(with any number of
params), PostgREST won't be able to resolve a POST request to
"my_func". For solving this, you can name the unnamed json param.
my_func(json) -> my_func(prm json)
steve-chavez
d4c6abbaec