BaseTools/Scripts/PatchCheck: Return CommitMessageCheck errors

REF: https://bugzilla.tianocore.org/show_bug.cgi?id=4693

Commit signatures are checked and error messages are logged but
errors are not captured and returned from find_signatures() in the
CommitMessageCheck class. This causes signature errors to be
silently ignored by CI.

Update logic in CommitMessageCheck class to return errors
detected in commit message signatures.

Cc: Rebecca Cran <rebecca@bsdio.com>
Cc: Liming Gao <gaoliming@byosoft.com.cn>
Cc: Bob Feng <bob.c.feng@intel.com>
Cc: Yuwei Chen <yuwei.chen@intel.com>
Cc: Michael Kubacki <mikuback@linux.microsoft.com>
Signed-off-by: Michael D Kinney <michael.d.kinney@intel.com>
Reviewed-by: Michael Kubacki <michael.kubacki@microsoft.com>
Reviewed-by: Rebecca Cran <rebecca@bsdio.com>

BaseTools/Scripts/PatchCheck.py

@@ -202,7 +202,7 @@ class CommitMessageCheck:
             if s[2] != ' ':
                 self.error("There should be a space after '" + sig + ":'")
 
-            EmailAddressCheck(s[3], sig)
+            self.ok &= EmailAddressCheck(s[3], sig).ok
 
         return sigs