Order entries in apex_info.pb

Adding the entries in apex_info.pb in sorted order makes it easier to
compare ota packages generated between the same source and target on
different computers/environments, ideally the generated ota zips should
be identical.

os.listdir() was used to find the apex files which should be
included in apex_info.pb. listdir() does not guarantee any order,
solution is to sort the result to ensure consistent order.

Bug: 278095305
Test: Manual. Confirm that apex_info.pb is generated sorted
    protoc --decode_raw < apex_info.pb
Change-Id: I2851d207f828a6ac31e63e20c9025965ac4b0eba
diff --git a/tools/releasetools/apex_utils.py b/tools/releasetools/apex_utils.py
index 40f7c92..d523701 100644
--- a/tools/releasetools/apex_utils.py
+++ b/tools/releasetools/apex_utils.py
@@ -626,7 +626,7 @@
     if os.path.isfile(deapexer_path):
       deapexer = deapexer_path
 
-  for apex_filename in os.listdir(target_dir):
+  for apex_filename in sorted(os.listdir(target_dir)):
     apex_filepath = os.path.join(target_dir, apex_filename)
     if not os.path.isfile(apex_filepath) or \
             not zipfile.is_zipfile(apex_filepath):