Add Cloudflare DNS as a private DNS provider

TODO: Add tests

Also includes:
commit d82a7a0585671903ba18cd1d8fab25d9275c2a25
Author: Oliver Scott <olivercscott@gmail.com>
Date:   Fri Jan 29 10:57:26 2021 -0500

    Fix Cloudflare private DNS provider

    Change-Id: I5932d8d7e82621220eb119a212ccecf15e284421
    (cherry picked from commit 24abf646a0df5e00285d1b698adec03eb897388f)

Change-Id: I7e8a320d47e7c5ddbcb9acfaf23032ae92d5d70d
(cherry picked from commit 96ce93f7bf7233008591d22a0d24a6d7cd0a94ff)
Signed-off-by: Mohammad Hasan Keramat J <ikeramat@protonmail.com>