Closes #9105.

Motivation / Problem

#9105 asks for better ability to match clientid + ip + username. Currently there isn't a single place this is logged, so tools etc can't pick up on this without difficult complexity on their side.

Description

Where #9105 presents some of this information via chat, of which I am not a fan (See #9105 (comment) for details), instead this PR presents the log in a single message.

Another difference to #9105 has to do with how loud we want connects to be. With this PR, this is what a normal connect looks like:

[2021-09-18 12:04:53] dbg: [net] [server] Client connected from 172.31.242.231 on frame 243
[2021-09-18 12:04:53] dbg: [net] [server] Client #2 closed connection
[2021-09-18 12:04:54] dbg: [net] [server] Client connected from 172.31.242.231 on frame 282
[2021-09-18 12:04:55] ‎*** TrueBrain #1 has joined the game (Client #3)
[2021-09-18 12:04:55] dbg: [net] [server] Client #3 (172.31.242.231) joined as TrueBrain #1

The first 2 lines are the server being queried by the client. The last 3 lines is a client joining (and has not left yet).

I went for only logging the "joined" when the name was known, so there is a single log message stating the client ID, the client IP and the client name. #9105 also adds a log message when the connection is assigned to a client ID, adding another message for only stating client ID + client IP. I can see the use of that, but it also makes the logs even more verbose. I am fully open to be convinced that is a good idea however :)

I also changed the "closed connection" message, to make the connect, join, and close message look alike. This should make it easier on tooling to deal with this.

Limitations

Checklist for review

Some things are not automated, and forgotten often. This list is a reminder for the reviewers.

• The bug fix is important enough to be backported? (label: 'backport requested')
• This PR touches english.txt or translations? Check the guidelines
• This PR affects the save game format? (label 'savegame upgrade')
• This PR affects the GS/AI API? (label 'needs review: Script API')
  • ai_changelog.hpp, gs_changelog.hpp need updating.
  • The compatibility wrappers (compat_*.nut) need updating.
• This PR affects the NewGRF API? (label 'needs review: NewGRF')
  • newgrf_debug_data.h may need updating.
  • PR must be added to API tracker