Automatically greylist code in 3P packages

generate_hidden_api_lists now receives a file containing package names
which need to be greylisted (although it could be made to work with any
api list required).
Also took the opportunity to clean up the tests to reflect the more
strict code.

Bug: 129387816
Test: m appcompat
Test: frameworks/base/tools/hiddenapi/generate_hiddenapi_lists_test.py
Change-Id: I619f8581d166aa48eda572bc0053d8739d6420eb
diff --git a/config/hiddenapi-greylist-packages.txt b/config/hiddenapi-greylist-packages.txt
new file mode 100644
index 0000000..cae3bd9
--- /dev/null
+++ b/config/hiddenapi-greylist-packages.txt
@@ -0,0 +1,2 @@
+org.ccil.cowan.tagsoup
+org.ccil.cowan.tagsoup.jaxp