Refactors tests folder to separate different modules

Each module has a different folder and they do not share methods now. At some point they should be split in different repos

test/common/unit/conftest.py

@@ -0,0 +1,7 @@
+import random
+
+
+def get_random_value_hex(nbytes):
+    pseudo_random_value = random.getrandbits(8 * nbytes)
+    prv_hex = "{:x}".format(pseudo_random_value)
+    return prv_hex.zfill(2 * nbytes)