Patch URL from pull requests should use full index to maintain stable contents

[zmughal]

The output of URLs with the .patch suffix should be similar to:

git show --full-index HEAD

otherwise tools that use the patches with a checksum of the contents can have different contents based on how much git decides to abbreviate the objects.

I have come across this here: microsoft/vcpkg#22681 (comment).

[dg0yt]

It seems like there is already an undocumented option: ?full_index=1
https://github.com/orgs/community/discussions/46034#discussioncomment-4846112