[VOL-5100] - periodic-voltha-test-bbsim

jjb/pipeline/voltha/master/bbsim-tests.groovy
---------------------------------------------
  o misc npm-groovy-lint cleanups:
    - indentation, quotes, typed vars, etc.
    - convert tabs to space (expand -i -t 8)
  o Stage('Install Kind')
    - wrap install_kind call in a script{} block for evaluation.
    - no primitives available like sh() to provide needed script{} context.
  o Re-enable IAM method now that branch_name is fixed.

makefiles/lint/include.mk
makefiles/lint/groovy/include.mk
makefiles/lint/groovy/install.mk
--------------------------------
  o (WIP) Add skeleton targets for lint-groovy able to install
    npm-groovy-lint on demand for local use.

Change-Id: Ifbf72ae9cb021d28c15a783454278ac2c680e45e
diff --git a/vars/showCommands.groovy b/vars/showCommands.groovy
index 58108ea..9e83ab9 100644
--- a/vars/showCommands.groovy
+++ b/vars/showCommands.groovy
@@ -27,7 +27,7 @@
 // -----------------------------------------------------------------------
 // -----------------------------------------------------------------------
 void run_cmd(String command) {
-    String buffer [
+    String buffer = [
         "Running command: $command",
     ]