api/types: consolidate types package

To simplify use of types, we have consolidate the packages for the mount
and descriptor protobuf types into a single Go package. We also drop the
versioning from the type packages, as these types will remain the same
between versions.

Signed-off-by: Stephen J Day <stephen.day@docker.com>

api/types/mount.proto

@@ -0,0 +1,29 @@
+syntax = "proto3";
+
+package containerd.types;
+
+import "gogoproto/gogo.proto";
+
+option go_package = "github.com/containerd/containerd/api/types;types";
+
+// Mount describes mounts for a container.
+//
+// This type is the lingua franca of ContainerD. All services provide mounts
+// to be used with the container at creation time.
+//
+// The Mount type follows the structure of the mount syscall, including a type,
+// source, target and options.
+message Mount {
+	// Type defines the nature of the mount.
+	string type = 1;
+
+	// Source specifies the name of the mount. Depending on mount type, this
+	// may be a volume name or a host path, or even ignored.
+	string source = 2;
+
+	// Target path in container
+	string target = 3;
+
+	// Options specifies zero or more fstab style mount options.
+	repeated string options = 4;
+}