Add android resource files to DEFAULT_FILES_TO_CHECK.

The existing licence regex assumed each line would start with an unknown
and optional comment delimiter, followed by a required space. However
the standard way to write the licence in XML files uses a multi-line
comment, each individual line simply starts with the licence text, no
delimiter or space. The license check thus needed to be updated to make
the space optional as well.

Bug: 407060754
Change-Id: I4a83dd9408de890593952e441ba6b650f726907c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/6409392
Commit-Queue: Sky Malice <skym@chromium.org>
Reviewed-by: Andy Perelson <ajp@google.com>
Reviewed-by: Yiwei Zhang <yiwzhang@google.com>

presubmit_support.py

@@ -574,6 +574,7 @@ class InputApi(object):
         r'.+\.mojom$',
         r'.+\.fidl$',
         r'.+\.rs$',
+        r'.+\/res\/.+\.xml$',
     )
 
     # Path regexp that should be excluded from being considered containing