OF-2526 Support SystemD for Debian

[stokito]

https://igniterealtime.atlassian.net/browse/OF-2526

I added the openfire.service to run the Openfire directly from SystemD.
The init.d script remains and even installed but it looks like it's not used if the unit's service file exists.
The SystemD itself will call the openfire.sh script. So I added the script to be installed into /usr/share/openfire/bin/openfire.sh. The script itself is has a problem with detection of OPENFIRE_HOME when the value of the var is overwritten few times. I didn't fixed that.

The existing file /etc/default/openfire is also supported by the SystemD unit.

There are additional commits to improve:

1. Use Runtive.version() to compare JRE version. It works correctly with 23-ea JDK version.
2. Added UFW firewall rules to make it easier to open ports. The Openfire has a lot of ports and it's difficult to collect the full list of them. The 8010 port is mentioned as Direct File Transfers and I'm not sure if this is a server thing of c2c connections. I added it anyway.
3. Added openfire.slice file to easier limit resources by editing it with sudo systemctl edit openfire.slice. The JRE by default uses only 25% of total RAM. So many servers may simply not use the whole RAM that they have. We may change this with Java's -Xmx but I think it would be more correct to use the whole RAM with the -XX:MaxRAMPercentage=100 but limit with the SystemD slice settings if needed. This will be simpler for people who aren't familiar with Java options to reuse their existing knowledge.

[Fishbowler]

Rebased

[Fishbowler]

Given that the ports are configurable, wouldn't these need to be set at runtime?

[stokito]

I don't know if it possible. I think that 99% will leave a default. At least this should help to beginner users.

[Fishbowler]

If I wanted to test this, how would I go about it?

[stokito]

As far I understood the connection manager is in fact an internal thing. And it probably not used so often. Then I think it would be better to remove the rule. Please confirm

[stokito]

To test it you need to build a debian package:

mvn package
./main/build/debian/build_debs.sh

Then install the deb package

sudo dpkg -i ./distribution/target/debian/openfire.deb

Now you can see a status of the service:

systemctl status openfire

to see the unit use:

systemctl cat openfire

Restart, stop, start:

systemctl restart openfire
systemctl stop openfire
systemctl start openfire

The old sysinit script also should work:

/etc/init.d./openfire start