Add apex info to the streaming property file

So updaters can streaming download the file, and query the apex info
inside the file.

Bug: 190244686
Test: generate an OTA package, check the streaming property
Change-Id: I17078d3f8d60ca53c6afe82f74b232e2fb242467

tools/releasetools/test_ota_from_target_files.py

@@ -863,6 +863,7 @@ class StreamingPropertyFilesTest(PropertyFilesTestCase):
         property_files.required)
     self.assertEqual(
         (
+            'apex_info.pb',
             'care_map.pb',
             'care_map.txt',
             'compatibility.zip',
@@ -962,6 +963,7 @@ class AbOtaPropertyFilesTest(PropertyFilesTestCase):
         property_files.required)
     self.assertEqual(
         (
+            'apex_info.pb',
             'care_map.pb',
             'care_map.txt',
             'compatibility.zip',