send-key: Defining the public API

Add public virDomainSendKey() and enum libvirt_keycode_set
for the @codeset.

Python version of virDomainSendKey() has not been implemented yet,
it will be done soon.

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>

generator.py

@@ -362,6 +362,7 @@ skip_impl = (
     'virNodeDeviceListCaps',
     'virConnectBaselineCPU',
     'virDomainRevertToSnapshot',
+    'virDomainSendKey',
 )