runtime: add support for SGX

Support the `sgx.intel.com/epc` annotation that is defined by the intel
k8s plugin. This annotation enables SGX. Hardware-based isolation and
memory encryption.

For example, use `sgx.intel.com/epc = "64Mi"` to create a container
with 1 EPC section with pre-allocated memory.

At the time of writing this patch, SGX patches have not landed on the
linux kernel project.
The following github kernel fork contains all the SGX patches for the
host and guest: https://github.com/intel/kvm-sgx

fixes #483

Signed-off-by: Julio Montes <julio.montes@intel.com>

src/runtime/pkg/katautils/config_test.go

@@ -83,6 +83,7 @@ func createAllRuntimeConfigFiles(dir, hypervisor string) (config testRuntimeConf
 	disableNewNetNs := false
 	sharedFS := "virtio-9p"
 	virtioFSdaemon := path.Join(dir, "virtiofsd")
+	epcSize := int64(0)
 
 	configFileOptions := ktu.RuntimeConfigOptions{
 		Hypervisor:           "qemu",
@@ -165,6 +166,7 @@ func createAllRuntimeConfigFiles(dir, hypervisor string) (config testRuntimeConf
 		SharedFS:              sharedFS,
 		VirtioFSDaemon:        virtioFSdaemon,
 		VirtioFSCache:         defaultVirtioFSCacheMode,
+		SGXEPCSize:            epcSize,
 	}
 
 	agentConfig := vc.KataAgentConfig{