openbmc-build-scripts: add vim to container

There are times when interactively working within a CI unit test docker
container that having vim available is useful.

Change-Id: I564e1882e325e5b871eda9c0defaec51d4a7bf0d
Signed-off-by: Andrew Geissler <geissonator@yahoo.com>
diff --git a/scripts/build-unit-test-docker b/scripts/build-unit-test-docker
index 200d464..4b79799 100755
--- a/scripts/build-unit-test-docker
+++ b/scripts/build-unit-test-docker
@@ -814,6 +814,7 @@
     systemd \
     valgrind \
     valgrind-dbg \
+    vim \
     wget \
     xxd