Populate the global keys AWS sets on every request from who makes it and
what it is made on: aws:ResourceAccount (the account owning the target
resource), aws:PrincipalOrgID / aws:PrincipalOrgPaths when the
principal’s account (principal_account) is in an organization,
aws:ResourceOrgID / aws:ResourceOrgPaths when the resource’s account
is, and aws:ViaAWSService (false unless a service set it for a call it
forwards). org_of gives an account’s organization id and path. A value
already present wins.
The server-wide buffered request body cap in bytes, from
FAKECLOUD_MAX_REQUEST_BODY_BYTES (default 1 GiB). Public so buffered
sub-proxies (e.g. the CloudFront viewer data plane) apply the SAME cap as
direct traffic rather than an inconsistent limit of their own.