ci: add FIH hardening tests to workflows

Add workflows to run FIH tests using GH actions. Update scripts to add
parsing of FIH parameters from a env matrix and disable docker caching
when running on GH.

Signed-off-by: Fabio Utzig <utzig@apache.org>
diff --git a/ci/fih-tests_install.sh b/ci/fih-tests_install.sh
index fb6e0fb..4e38627 100755
--- a/ci/fih-tests_install.sh
+++ b/ci/fih-tests_install.sh
@@ -25,6 +25,8 @@
 [[ -f $CACHED_IMAGE ]] && (gzip -dc $CACHED_IMAGE | docker load)
 
 if [[ $? -ne 0 ]]; then
-  docker pull mcuboot/$IMAGE
-  docker save mcuboot/$IMAGE | gzip > $CACHED_IMAGE
+    docker pull mcuboot/$IMAGE
+    if [[ $GITHUB_ACTIONS != true ]]; then
+        docker save mcuboot/$IMAGE | gzip > $CACHED_IMAGE
+    fi
 fi