Upgrades to containerd, fix deprecations upstream

* Fixes upstream deprecations for containerd
* Fixes deprecations in ioutil package usage
* Break out separate files for function handlers
* Upgrades containerd to 1.7.22
* Fixes default namespace functionality
* Pre-deploy checks as per license agreement
* Removes extra log messages for payload in HTTP handlers, you
can enable FAAS_DEBUG=1 in the CLI instead to see this from
the client's perspective
* Add additional Google DNS server 8.8.4.4 for functions

Signed-off-by: Alex Ellis (OpenFaaS Ltd) <alexellis2@gmail.com>

vendor/github.com/moby/sys/userns/userns_linux_fuzzer.go

@@ -0,0 +1,8 @@
+//go:build linux && gofuzz
+
+package userns
+
+func FuzzUIDMap(uidmap []byte) int {
+	_ = uidMapInUserNS(string(uidmap))
+	return 1
+}