Data disk is an important feature for instances and images, this
patch implements the basic functionality of it. More work needs
to be done to make it friendly to users. Docs has pointed out
current limitation.
Also update dependencies because this feature requires new code in
tencentcloud go sdk.
Tencent Cloud key pair cannot be removed if it is in a image, so
when user doesn't specify any log in method, such as ssh_password,
temporary key pair will be created and used, which eventually will
always fail.
This patch detach temporary key pair before creating image, so in
cleanup step, it can be deleted correctly.
Note that if user specifies a private key pair, we do not detach it,
because user might want to use it when creating new instances from this
image.
