cmd-build-with-buildah: add --force for compatibility

There is no good change detection right now on the container-native
side. Hermetic Konflux builds should help there, but I'd also like to
make our builds reproducible which is the ultimate solution to this
though less efficient (we'd still do the build, but since we'd get
the same digest, it'd be a no-op -- this is why it's still useful even
with reproducible builds to have good "path change" triggers like what
Konflux offers).

Author: jlebon

src/cmd-build-with-buildah

@@ -22,6 +22,7 @@ Usage: coreos-assembler build-with-buildah
                          non-strict build.
   --skip-prune           Skip prunning previous builds
   --parent-build=VERSION This option does nothing and is provided for backwards compatibility.
+  --force                This option does nothing and is provided for backwards compatibility.
 EOF
 }
 
@@ -31,7 +32,7 @@ DIRECT=
 AUTOLOCK_VERSION=
 SKIP_PRUNE=
 rc=0
-options=$(getopt --options h,d --longoptions help,version:,versionary,direct,autolock:,skip-prune,parent-build: -- "$@") || rc=$?
+options=$(getopt --options h,d --longoptions help,version:,versionary,direct,autolock:,skip-prune,parent-build:,force -- "$@") || rc=$?
 [ $rc -eq 0 ] || {
     print_help
     exit 1
@@ -63,6 +64,8 @@ while true; do
         --parent-build)
             shift
             ;;
+        --force)
+            ;;
         --)
             shift
             break