Move scripts to python3

Today we are in a limbo where some scripts are run with
python (which defaults to python2 on some systems) some
other with python3. This normalizes everything* to python3.
In the process of doing so:
 - Fixed a sorting issue in gen_bazel and gen_android_bp,
   as it was causing different outputs when running with
   the two different versions of python.
 - Got rid of some vestigial scripts we no longer use.
 - Got rid of the shebang from some scripts that are executed
   only by GN. Having a shebang is misleading because in reality
   GN is the one deciding which version of python to run.

I left only few others that are too expensive to test
right now like some infra bots and the heap profile tools.

Change-Id: Iab5b28196c5a92603745a0dccad17831c43ee590

tools/run_android_emulator

diff --git a/tools/run_android_emulator b/tools/run_android_emulator
index 7852919..6f6ffcf 100755
--- a/tools/run_android_emulator
+++ b/tools/run_android_emulator
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 # Copyright (C) 2017 The Android Open Source Project
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
@@ -15,7 +15,6 @@
 
 import argparse
 import os
-import shutil
 import sys
 
 
@@ -55,8 +54,8 @@
       os.path.join(aosp_path, 'vendor-qemu.img'), '-data',
       os.path.join(aosp_path, 'userdata-qemu.img')
   ]
-  print '\n'.join('='.join(x) for x in env.items())
-  print ' '.join([emulator_bin] + emulator_args)
+  print('\n'.join('='.join(x) for x in env.items()))
+  print(' '.join([emulator_bin] + emulator_args))
   if args.pid:
     with open(args.pid, 'w') as f:
       f.write(str(os.getpid()))