v2api/reverse: move old fusefrontend_reverse out of the way

fusefrontend_reverse -> fusefrontend_reverse_v1api

internal/fusefrontend_reverse/r_node.go

@@ -1,20 +0,0 @@
-package fusefrontend_reverse
-
-import (
-	"github.com/hanwen/go-fuse/v2/fs"
-
-	"github.com/rfjakob/gocryptfs/internal/contentenc"
-	"github.com/rfjakob/gocryptfs/internal/fusefrontend"
-	"github.com/rfjakob/gocryptfs/internal/nametransform"
-)
-
-// RNode is a file or directory in the filesystem tree
-// in a `gocryptfs -reverse` mount.
-type RNode struct {
-	fs.Inode
-}
-
-func NewRootNode(args fusefrontend.Args, c *contentenc.ContentEnc, n nametransform.NameTransformer) *RNode {
-	// TODO
-	return &RNode{}
-}