[newauth] Accept standard Git bool values

Just some "syntactic" sugar (at the very least we should probably have
used 'true' from the beginning)

https://git-scm.com/docs/git-config#Documentation/git-config.txt-boolean

Bug: b/348024314
Change-Id: I9ec3b12012444662289619ac955885e732945fe2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/5641085
Reviewed-by: Gavin Mak <gavinmak@google.com>
Commit-Queue: Allen Li <ayatane@chromium.org>

newauth.py

@@ -12,9 +12,13 @@ import scm
 
 def Enabled() -> bool:
     """Returns True if new auth stack is enabled."""
-    return scm.GIT.GetConfig(os.getcwd(), 'depot-tools.usenewauthstack') == '1'
+    return scm.GIT.GetConfig(os.getcwd(),
+                             'depot-tools.usenewauthstack') in ('yes', 'on',
+                                                                'true', '1')
 
 
 def SkipSSO() -> bool:
     """Returns True if skip SSO is set."""
-    return scm.GIT.GetConfig(os.getcwd(), 'depot-tools.newauthskipsso') == '1'
+    return scm.GIT.GetConfig(os.getcwd(),
+                             'depot-tools.newauthskipsso') in ('yes', 'on',
+                                                               'true', '1')