Add fuzz tests for storage_fs (#601)

This commit uses native go fuzzing to fuzz test implementations
of storage in storage_fs.

moved fuzzing testdata for storage_fs in separate repo

added make target and script for importing fuzz data and running all fuzz tests

Signed-off-by: Alex Stan <alexandrustan96@yahoo.ro>

test/scripts/fuzzAll.sh

@@ -0,0 +1,18 @@
+#!/bin/bash
+
+set -e
+
+fuzzTime=${1:-10}
+
+files=$(grep -r --include='**_test.go' --files-with-matches 'func Fuzz' .)
+
+for file in ${files}
+do
+    funcs=$(grep -oP 'func \K(Fuzz\w*)' $file)
+    for func in ${funcs}
+    do
+        echo "Fuzzing $func in $file"
+        parentDir=$(dirname $file)
+        go test $parentDir -run=$func -fuzz=$func$ -fuzztime=${fuzzTime}s -tags sync,metrics,search,scrub,ui_base,containers_image_openpgp | grep -oP -x '^(?:(?!\blevel\b).)*$'
+    done
+done