Enable protected_fifos and protected_regular

See “protected regular and fifo files” in https://outflux.net/blog/archives/2018/10/22/security-things-in-linux-v4-19/ and https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=30aba6656f61ed44cba445a3c0d38b296fa9e8f5.

Feature Branch: feature/16072-protected-regular-and-fifo-files+force-all-tests

Related issues

Blocked by #16073 (closed)
Blocks #15507 (closed)
Blocked by #16349 (closed)
Blocks #16352 (closed)

Original created by @intrigeri on 16072 (Redmine)

To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information