net/amnezia-tools: Improve port

- Move "-tools" from PORTNAME to PKGNAMESUFFIX.
- Properly use PREFIX and ETCDIR.
- Add shebangfix.
- Make portclippy happy.
- Fix manpages.
- Fix bash completion.

PR:		288730
Co-authored-by: Vladimir Druzenko <vvd@FreeBSD.org>