iar-dockerfiles: init commit

Jenking agent image with IAR toolchain installed for TF-M

Change-Id: I4455a9b0dde01231af329505105824c282e04348
Signed-off-by: Arthur She <arthur.she@linaro.org>
diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..b08be19
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+*/.docker-tag