add execution time of ValidateOutput to BaseTest output

To monitor and easily check that the ValidateOutput call doesn't take large amounts of time it is handy to have the timing be part of the reported output of BaseTest.py

Triggered by a test in LHCb where LineSkipper was taking many minutes to run.

cc @sponce

GaudiPolicy/python/GaudiTesting/BaseTest.py

@@ -130,6 +130,7 @@ class BaseTest(object):
         self.proc = None
         self.stack_trace = None
         self.basedir = os.getcwd()
+        self.validate_time = None
 
     def run(self):
         logging.debug("running test %s", self.name)
@@ -257,9 +258,11 @@ class BaseTest(object):
                         f"completed test {self.name} with returncode = {self.returnedCode}"
                     )
                     logging.debug("validating test...")
+                    val_start_time = time.perf_counter()
                     self.result, self.causes = self.ValidateOutput(
                         stdout=self.out, stderr=self.err, result=self.result
                     )
+                    self.validate_time = round(time.perf_counter() - val_start_time, 2)
                 else:
                     logging.debug(f"skipped test {self.name}")
                     self.status = "skipped"
@@ -302,6 +305,7 @@ class BaseTest(object):
             "Program Name": "program",
             "Name": "name",
             "Validator": "validator",
+            "Validation execution time": "validate_time",
             "Output Reference File": "reference",
             "Error Reference File": "error_reference",
             "Causes": "causes",