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_fixer.py b/scripts/manifest_fixer.py
index 55d0fd1..d80a617 100755
--- a/scripts/manifest_fixer.py
+++ b/scripts/manifest_fixer.py
@@ -352,7 +352,7 @@
     if args.extract_native_libs is not None:
       add_extract_native_libs(doc, args.extract_native_libs)
 
-    with open(args.output, 'wb') as f:
+    with open(args.output, 'w') as f:
       write_xml(f, doc)
 
   # pylint: disable=broad-except