feat: Add Automatic Gamedata Updates

[roflmuffin]

Adds a basic automatic gamedata update system which will check the latest gamedata.json file from a CDN and download the new gamedata file if the ETag is different.

Gamedata updates can be completed through a PR to the CS2-Gamedata repo which will verify valid sigs and then sync with the CDN on merge.

[Copilot]

Pull Request Overview

Adds a new automatic gamedata update mechanism that checks a remote ETag and downloads an updated gamedata.json when needed.

• Introduces TryUpdateGameConfig() in a new updater module to fetch and store gamedata based on ETag differences
• Adds AutoUpdateEnabled and AutoUpdateURL settings to core config (native and managed) and example config
• Updates build scripts (CMake and platform makefiles) to include OpenSSL and new updater source files

Reviewed Changes

Copilot reviewed 10 out of 11 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
src/mm_plugin.cpp	Invokes the updater when AutoUpdateEnabled is true
src/core/gameconfig_updater.h / cpp	New HTTP-based ETag checker and downloader for gamedata.json
src/core/coreconfig.h / coreconfig.cpp	Added AutoUpdateEnabled and AutoUpdateURL config fields
managed/CounterStrikeSharp.API/Core/CoreConfig.cs	Exposed new update settings in the managed CoreConfigData
makefiles/windows.base.cmake	Linked OpenSSL libraries for SSL support
makefiles/linux.base.cmake	Linked OpenSSL libraries for SSL support
CMakeLists.txt	Added OpenSSL find and listed updater headers & sources
configs/addons/.../core.example.json	Updated example JSON with new auto-update settings

Comments suppressed due to low confidence (3)

src/core/gameconfig_updater.cpp:21

• [nitpick] The @return tag is present but lacks a description. Please add a brief explanation of what the boolean return value indicates (e.g., true on success, false on failure).

/// @return

src/core/gameconfig_updater.cpp:22

• [nitpick] Consider adding unit or integration tests for TryUpdateGameConfig() to cover scenarios such as unchanged ETag, successful download, and various failure modes (network error, file I/O error).

bool TryUpdateGameConfig()

src/mm_plugin.cpp:125

• The call to update::TryUpdateGameConfig() uses the unqualified update namespace. The function is declared in counterstrikesharp::update, so either qualify the call (counterstrikesharp::update::TryUpdateGameConfig()) or add an appropriate using declaration.

        if (!update::TryUpdateGameConfig())

[KillStr3aK]

don't forget to update the docs page with the new core config entries