Performs one fetch exchange — request, response headers, AND body read —
under a single abort timer, so a hung PSP connection can never hang the
host's request handler. Any failure (abort or network) is mapped through
onFailure; an HTTP error status is NOT a failure here — the caller maps
response.ok itself.
Performs one fetch exchange — request, response headers, AND body read — under a single abort timer, so a hung PSP connection can never hang the host's request handler. Any failure (abort or network) is mapped through
onFailure; an HTTP error status is NOT a failure here — the caller mapsresponse.okitself.