cros_build_lib: rename RunCommand to run

This aligns with the new subprocess.run API.

RunCommand -> run.
SudoRunCommand -> sudo_run.
DebugRunCommand -> dbg_run.

BUG=chromium:1006587
TEST=`./run_tests` passes

Change-Id: I78ebd4e08176d7874b3d3fe537b6ceb292b0241b
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/chromite/+/1818782
Tested-by: Mike Frysinger <vapier@chromium.org>
Commit-Queue: Mike Frysinger <vapier@chromium.org>
Reviewed-by: Chris McDonald <cjmcdonald@chromium.org>
diff --git a/api/router.py b/api/router.py
index d90e722..ce03139 100644
--- a/api/router.py
+++ b/api/router.py
@@ -264,7 +264,7 @@
           cmd.append('--validate-only')
 
         try:
-          result = cros_build_lib.RunCommand(
+          result = cros_build_lib.run(
               cmd,
               enter_chroot=True,
               chroot_args=chroot.get_enter_args(),