pw_presubmit: Run --step steps before prog steps

Run steps included via --step arguments before steps from programs.

Change-Id: I1143c9a7f46a52bb7fc0c37167b2a0bd9636ecba
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/127190
Commit-Queue: Auto-Submit <auto-submit@pigweed.google.com.iam.gserviceaccount.com>
Pigweed-Auto-Submit: Rob Mohr <mohrr@google.com>
Reviewed-by: Tim Laurence <timlaurence@google.com>
diff --git a/pw_presubmit/py/pw_presubmit/cli.py b/pw_presubmit/py/pw_presubmit/cli.py
index e0ffe29..d29dd16 100644
--- a/pw_presubmit/py/pw_presubmit/cli.py
+++ b/pw_presubmit/py/pw_presubmit/cli.py
@@ -318,9 +318,9 @@
         final_program = program[0]
     else:
         steps: List[presubmit.Check] = []
+        steps.extend(step)
         for prog in program:
             steps.extend(prog)
-        steps.extend(step)
         final_program = presubmit.Program('', steps)
 
     if substep and len(final_program) > 1: