Add scheduled exit support

[MadMaxMangos]

Add scheduled maintenance restart/shutdown support to mangosd

Adds disabled-by-default scheduled shutdown/restart support to mangosd, replacing the previous need for external Remote Admin scripts to drive weekly maintenance restarts.

Behavior:

• Adds ScheduledExit config support to mangosd.conf.dist.
• Checks local server wall-clock day and time.
• Starts the existing shutdown/restart countdown path at the configured scheduled minute.
• Supports configurable delay, warning milestones, and warning text.
• Ships legacy-style weekly restart warning defaults at 15, 10, 5, and 1 minutes.
• Sends configured warning text through SERVER_MSG_CUSTOM / SMSG_SERVER_MESSAGE, so it appears in the same yellow server-message channel as built-in shutdown/restart countdowns rather than as a GM-style announce.
• Skips scheduled firing if another shutdown/restart is already in progress.
• Adds startup-minute suppression to prevent restart loops if the daemon comes back up inside the same scheduled minute.

Validation:

• scheduled_exit_tests.exe passed.
• game and mangosd rebuilt successfully.
• git diff --check passed.
• Full 15-minute scheduled restart cadence tested twice with the 900/600/300/60 warning sequence.
• SERVER_MSG_CUSTOM behavior verified against the 1.12.1 client handler and ServerMessages.dbc row 3 %s.

Notes:

• This PR assumes the related realmd scheduled-exit PR handles service-only realm-list daemon restarts.
• The feature is disabled by default.
• No database changes.

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This change is 

[codacy-production]

Up to standards ✅

🟢 Issues 0 issues

Results:
0 new issues

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🟢 Metrics 92 complexity · 5 duplication

Metric	Results
Complexity	92
Duplication	5

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[AppVeyorBot]

✅ Build Mangos ZERO Server 22.04.266-smijsmij completed (commit 1760ed3bdd by @MadMaxMangos)

[AppVeyorBot]

✅ Build Mangos ZERO Server 22.04.266-euponhjt completed (commit 7950aedd5d by @MadMaxMangos)

[billy1arm]

There are two issues I see:

1. Both will need to have the conf version numbers updated; these are in MangosParams.cmake

The format is normally in the format YYYYMMDD00

2. Rather than those strings being in the conf file, they should be in the database mangos_strings as new entries and called from there; this allows for easy localisation.

[AppVeyorBot]

❌ Build Mangos ZERO Server 22.04.266-bcvtiovw failed (commit 89f01fea4f by @MadMaxMangos)

[billy1arm]

can you change the starting id from 1717 to 1730 onwards to allow the same code to be used across the cores.
MangosThree has some additional messages