[SDFAB-1197] First stab to update ONOS to py3

Update has been performed only on the scripts and the
executables strictly necessary for the following use cases:

- Build (including Intellij)
- Tests (including Intellij)
- Docker build (including dev and yourkit)
- Upload snapshot (including local)
- Release

Finally, fix the ability to run ONOS using onos-local targets,
stc and docker stc (aka up4 stc env). Last but not least, updated
the azul image to a newer one which exports also the PYTHONENCODING

Change-Id: Ie96f3a9c76dbba83b1fc3896a372f1045d3d7ccc
diff --git a/tools/build/bazel/dependencies_pom_generator.py b/tools/build/bazel/dependencies_pom_generator.py
index f2df0c2..8c6483f 100755
--- a/tools/build/bazel/dependencies_pom_generator.py
+++ b/tools/build/bazel/dependencies_pom_generator.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 # Copyright 2019-present Open Networking Foundation
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
@@ -20,7 +20,7 @@
 def resolve(mvn_coord):
     mvn_pieces = mvn_coord.split(":")
     if mvn_pieces[0] != "mvn":
-        raise ("Invalid Maven coordinate: %s" % mvn_coord)
+        raise ValueError("Invalid Maven coordinate: %s" % mvn_coord)
     return dict(
         groupId=mvn_pieces[1],
         artifactId=mvn_pieces[2],
@@ -79,7 +79,7 @@
                 dep_template.format(scope='test', **deps[x])
                 for x in test_deps])
         else:
-            for old, new in var_dict.items():
+            for old, new in list(var_dict.items()):
                 line = line.replace(old, new)
             new_lines.append(line)
 
@@ -111,7 +111,7 @@
     for var in args.vars:
         pieces = var.split('=')
         if len(pieces) != 2:
-            raise ("Invalid var '%s'" % var)
+            raise ValueError("Invalid var '%s'" % var)
         processed_vars["<!-- %s -->" % pieces[0]] = pieces[1]
 
     generate_pom(