GHSA-fj3h-2jc3-973v: Unbounded memory use on large request bodies

The makegraphqlfilter() and makegraphqlfiltersync() filters of juniperwarp read the whole body of a POST request into memory before they parsed the body. The filters had no limit on the size of the body. A client could thus send a large body and exhaust the memory of the server. The request needs no authentication.

juniperwarp 0.9.1 reads at most 2 MiB of a request body by default. The filters respond with 413 Payload Too Large to larger bodies. makegraphqlfilterwithbodylimit() and makegraphqlfiltersyncwithbodylimit() set another limit.