Tests: add WIITH_TESTS_BATCHED option to execute Blender once per test

Some tests like cycles, sequencer and compositor batch together multiple
tests in a single Blender invocation. This makes them run faster, but
makes debugging harder. This is an option to disable that batching.

Pull Request: https://projects.blender.org/blender/blender/pulls/114603

tests/python/eevee_next_render_tests.py

@@ -110,6 +110,7 @@ def create_argparse():
     parser.add_argument("-testdir", nargs=1)
     parser.add_argument("-outdir", nargs=1)
     parser.add_argument("-idiff", nargs=1)
+    parser.add_argument('--batch', default=False, action='store_true')
     return parser
 
 
@@ -138,7 +139,7 @@ def main():
     if test_dir_name.startswith('image'):
         report.set_fail_threshold(0.051)
 
-    ok = report.run(test_dir, blender, get_arguments, batch=True)
+    ok = report.run(test_dir, blender, get_arguments, batch=args.batch)
 
     sys.exit(not ok)