feat(short_sha): add a shortened sha commit id

tests/short_sha.bats

@@ -0,0 +1,19 @@
+#!/usr/bin/env bats
+
+@test "Short long hash" {
+  test_short_sha \
+    "a35a1a486a260cfd99c5b6f8c6034a2929ba9b3f" \
+    "a35a1a48"
+}
+
+# Load sluf_ref function
+source entrypoint.sh > /dev/null 2>&1
+
+test_short_sha(){
+  given="${1}"
+  expected="${2}"
+
+  actual="$(short_sha ${given})"
+  echo "expected : [${expected}], actual : [${actual}]"
+  [ "${actual}" == "${expected}" ]
+}