wic: add 'wic rm' command

Added empty 'wic rm' command that does nothing.
The functionality will be added by the next commits.

[YOCTO #11283]

(From OE-Core rev: f8e42c13609c482359fbdb225fb16a45101ae9ae)

Signed-off-by: Ed Bartosh <ed.bartosh@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

scripts/lib/wic/engine.py

@@ -340,6 +340,13 @@ def wic_cp(args, native_sysroot):
     disk = Disk(args.dest.image, native_sysroot)
     disk.copy(args.src, args.dest.part, args.dest.path)
 
+def wic_rm(args, native_sysroot):
+    """
+    Remove files or directories from the vfat partition of
+    partitioned image.
+    """
+    pass
+
 def find_canned(scripts_path, file_name):
     """
     Find a file either by its path or by name in the canned files dir.