Convert soong scripts to python 3

Except manifest_utils, which is used by
apexer.

Tests run:
m construct_context_test manifest_check_test manifest_fixer_test test_config_fixer_test
out/host/linux-x86/testcases/construct_context_test/x86_64/construct_context_test
out/host/linux-x86/testcases/manifest_check_test/x86_64/manifest_check_test
out/host/linux-x86/testcases/manifest_fixer_test/x86_64/manifest_fixer_test
out/host/linux-x86/testcases/test_config_fixer_test/x86_64/test_config_fixer_test

Bug: 203436762
Test: Tests listed above + presubmits
Change-Id: Ife75b3af1efc871a2d8521d26153a262573bb706
diff --git a/scripts/manifest_check.py b/scripts/manifest_check.py
index 8bed52a..c8d4f76 100755
--- a/scripts/manifest_check.py
+++ b/scripts/manifest_check.py
@@ -335,7 +335,7 @@
         if is_apk:
             aapt = args.aapt if args.aapt is not None else 'aapt'
             manifest = subprocess.check_output(
-                [aapt, 'dump', 'badging', args.input])
+                [aapt, 'dump', 'badging', args.input]).decode('utf-8')
         else:
             manifest = minidom.parse(args.input)
 
@@ -381,7 +381,7 @@
             if is_apk:
                 raise RuntimeError('cannot save APK manifest as XML')
 
-            with open(args.output, 'wb') as f:
+            with open(args.output, 'w') as f:
                 write_xml(f, manifest)
 
     # pylint: disable=broad-except