AppleHV enablement pass #2

* Use vfkit command line assembly
* Inject ignition file into guest using http over vsock
* Ready notification through use of vsock

[NO NEW TESTS NEEDED]

Signed-off-by: Brent Baude <bbaude@redhat.com>

vendor/github.com/gin-gonic/gin/render/protobuf.go

@@ -0,0 +1,36 @@
+// Copyright 2018 Gin Core Team. All rights reserved.
+// Use of this source code is governed by a MIT style
+// license that can be found in the LICENSE file.
+
+package render
+
+import (
+	"net/http"
+
+	"google.golang.org/protobuf/proto"
+)
+
+// ProtoBuf contains the given interface object.
+type ProtoBuf struct {
+	Data any
+}
+
+var protobufContentType = []string{"application/x-protobuf"}
+
+// Render (ProtoBuf) marshals the given interface object and writes data with custom ContentType.
+func (r ProtoBuf) Render(w http.ResponseWriter) error {
+	r.WriteContentType(w)
+
+	bytes, err := proto.Marshal(r.Data.(proto.Message))
+	if err != nil {
+		return err
+	}
+
+	_, err = w.Write(bytes)
+	return err
+}
+
+// WriteContentType (ProtoBuf) writes ProtoBuf ContentType.
+func (r ProtoBuf) WriteContentType(w http.ResponseWriter) {
+	writeContentType(w, protobufContentType)
+}