Add an option to disable Tart clipboard sharing (#475)

Expose noClipboard in VM creation, CLI inspection, and the API schema.
Pass --no-clipboard to Tart when requested. Clipboard sharing remains
enabled by default for existing VM specifications.

pkg/resource/v1/v1.go

@@ -33,6 +33,7 @@ type VM struct {
 	Headless        bool            `json:"headless,omitempty"`
 	Nested          bool            `json:"nested,omitempty"`
 	NoAudio         bool            `json:"noAudio,omitempty"`
+	NoClipboard     bool            `json:"noClipboard,omitempty"`
 
 	VMSpec
 	VMSpecReadOnly