Use run0 for privilege escalation

This removes the need for suid binaries like pkexec or sudo.

Requires a systemd version with run0 support.

initial release

supports

• adding Brave (stable, beta, nightly) via repofile download and placement
• adding Vivaldi (stable, snapshot) via manually writing the file
• x86_64 and arm64
• securing all .repo files with unix permissions and SELinux context fixes
• a few edge cases