runtime: add CPU cores and memory basic info for kata-env sub-command

Add host memory size(Total/Free/Avaiable) and CPU cores in host info
for `kata-runtime kata-env`.

Fixes: #405

Signed-off-by: bin liu <bin@hyper.sh>

src/runtime/cli/kata-env_generic_test.go

@@ -45,6 +45,9 @@ func testEnvGetEnvInfoSetsCPUTypeGeneric(t *testing.T) {
 	env, err := getEnvInfo(configFile, config)
 	assert.NoError(err)
 
+	// Free/Available are changing
+	expectedEnv.Host.Memory = env.Host.Memory
+
 	assert.Equal(expectedEnv, env)
 
 	assert.Equal(archRequiredCPUFlags, savedArchRequiredCPUFlags)