feat: use CMake and SDL3

Based on: https://github.com/Ravbug/sdl3-sample

config/README.md

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+# How to use these scripts
+
+For the most part, just run the scripts in this directory from this directory. 
+
+## Notes:
+- visionOS
+	- Requires CMake 3.28 or newer
+- Web
+ 	1. Install emsdk somewhere.
+  	2. On Windows hosts, run `config-web-win.bat` via the `emcmdprompt.bat` cmd in the emsdk root directory
+	3. On Unix hosts, first run `source emsdk_env.sh` (found in the emsdk root directory), then run `config-web-unix.sh` 
+	4. After the build completes, use `python3 -m http.server` in the build directory to make the page accessible.
+- Android
+	- There is no easy CMake config for this platform. Instead, follow the steps as outlined below. See the android GitHub action for more details. 
+	1. Install Android Studio + NDK from https://developer.android.com/studio
+ 	2. Copy `build.gradle` to `SDL/android-project/app/`. If you look inside `build.gradle`, you'll see `"../../../CMakeLists.txt"` as the path to the CMakeLists file. This points to the CMakeLists in this repo's root directory after it is copied. 
+  	3. `cd SDL/android-project/`
+  	4. `./gradlew assembleDebug`. You'll get an apk which you can then install onto a device. 

config/config-generic.sh

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+#!/bin/bash
+cd "${0%/*}"/
+
+cmake -B "../build/`uname`" -S ..

config/config-ios-xcode.sh

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+#!/bin/bash
+cd "${0%/*}"
+
+cmake -G "Xcode" -DCMAKE_SYSTEM_NAME="iOS" -B ../build/ios -S ..

config/config-mac-xcode.sh

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+#!/bin/bash
+cd "${0%/*}"
+
+cmake -G "Xcode" -B ../build/mac  -S ..

config/config-tvos-xcode.sh

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+#!/bin/bash
+cd "${0%/*}"
+
+cmake -G "Xcode" -DCMAKE_SYSTEM_NAME="tvOS" -B ../build/tvos -S ..

config/config-visionos-xcode.sh

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+#!/bin/bash
+
+# note: requires CMake 3.28 or newer
+
+cd "${0%/*}"
+
+cmake -G "Xcode" -DCMAKE_SYSTEM_NAME="visionOS" -S .. -B ../build/visionOS

config/config-web-unix.sh

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+#!/bin/bash
+cd "${0%/*}"
+
+emcmake cmake -S .. -B ../build/web

config/config-web-win.bat

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+@echo OFF
+
+emcmake cmake -S .. -B ..\build\web

config/config-win.bat

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+@echo OFF
+
+cmake -S .. -B ..\build\win