feat(rsdwserver): add RuneScape: Dragonwilds server

[JSaterdalen]

Description

Adds dedicated server support for RuneScape: Dragonwilds (Steam appid 4019830, native Linux 64-bit binary).

This PR supersedes #4893. @yourfate invited completion in their comment ("If anyone wants to complete this, feel free, I probably won't have time to work on this for a few months."); this branch picks up that work, finishes the open items, and has been tested on my own server.

differences from #4893:

• Uses shortname rsdw. Happy to revert if maintainers prefer rd.
• Adds fn_info_game_rsdw parsing the in-game DedicatedServer.ini for ServerName, OwnerId, WorldPassword, AdminPassword, DefaultWorldName (verified against the actual [/Script/Dominion.DedicatedServerSettings] section produced by the running server).
• Adds fn_info_messages_rsdw with the port table plus a "Game Settings" details block surfacing world name and owner ID.
• Adds rsdw to info_messages.sh's ports_edit_array so details shows the real INI path instead of UNKNOWN.
• Adds 2 GB minimum RAM check in check_system_requirements.sh (per official docs: 2 GB base + 1 GB per player).
• Uses Saved/Config/LinuxServer/ (the wiki says Linux/, but the server actually used LinuxServer/).
• Skips per-distro dep rows. UE5 dedicated servers installed via SteamCMD need no extra packages.

Follow-up (separate PR): a Game-Server-Configs template (rsdw/DedicatedServer.ini with SERVERNAME/ADMINPASSWORD placeholders) plus an install_config.sh block to seed the INI on first install.

Fixes #4891.

Type of change

• Bug fix (a change which fixes an issue).
• New feature (a change which adds functionality).
• New Server (new server added).
• Refactor (restructures existing code).
• Comment update (typo, spelling, explanation, examples, etc).

Testing

• Commands/tests run:
  • ./linuxgsm.sh rsdwserver
  • ./rsdwserver auto-install
  • ./rsdwserver start
  • ./rsdwserver details
  • ./rsdwserver stop
  • ./rsdwserver postdetails
  • shellcheck --severity=warning on info_game.sh, info_messages.sh, check_system_requirements.sh, and the new _default.cfg
• Result: All commands successful. INI parsing matches the actual section header [/Script/Dominion.DedicatedServerSettings] and the keys the server writes on first launch.
• Environment used (distro/version): Debian GNU/Linux 12 (bookworm), x86_64, glibc 2.36, kernel 6.8.12 (LXC). Target distro per serverlist.csv is ubuntu-24.04; Ubuntu 24.04 verification still pending.

Risk and rollback

• Risk level: low
• Rollback plan: revert the three commits on this branch

Breaking changes

• No breaking changes.
• Breaking changes included (describe below).

Documentation impact

• No documentation update required.
• User documentation update required.
• Developer documentation update required.

A new page under LinuxGSM-Docs/game-servers/ for rsdwserver should be added once this lands. Happy to open the docs PR as a follow-up.

Checklist

PR will not be merged until all steps are complete.

• This pull request links to an issue.
• This pull request uses the develop branch as its base.
• This pull request subject follows the Conventional Commits standard.
• This code follows the style guidelines of this project.
• I have performed a self-review of my code.
• I have provided a detailed enough description of this PR.

Documentation

If documentation does need updating either update it by creating a PR (preferred) or request a documentation update.

• User docs: https://github.com/GameServerManagers/LinuxGSM-Docs
• Dev docs: https://github.com/GameServerManagers/LinuxGSM-Dev-Docs