[docs] Bring back the Options page, and clean up LLM policy (#3649)

Signed-off-by: crueter <crueter@eden-emu.dev>
Reviewed-on: https://git.eden-emu.dev/eden-emu/eden/pulls/3649

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+# CMake Options
+
+To change these options, add `-DOPTION_NAME=NEWVALUE` to the command line.
+
+- On Qt Creator, go to Project -> Current Configuration
+
+Notes:
+
+- Defaults are marked per-platform.
+- "Non-UNIX" just means Windows/MSVC and Android (yes, macOS is UNIX
+- Android generally doesn't need to change anything; if you do, go to `src/android/app/build.gradle.kts`
+- To set a boolean variable to on, use `ON` for the value; to turn it off, use `OFF`
+- If a variable is mentioned as being e.g. "ON" for a specific platform(s), that means it is defaulted to OFF on others
+- TYPE is always boolean unless otherwise specified
+- Format:
+  - `OPTION_NAME` (TYPE DEFAULT) DESCRIPTION
+
+## Options
+
+### Dependencies
+
+These options control dependencies.
+
+- `YUZU_USE_BUNDLED_FFMPEG` (ON for non-UNIX) Download a pre-built and configured FFmpeg
+- `YUZU_USE_EXTERNAL_FFMPEG` (ON for Solaris) Build FFmpeg from source
+- `YUZU_DOWNLOAD_ANDROID_VVL` (ON) Download validation layer binary for Android
+- `YUZU_DOWNLOAD_TIME_ZONE_DATA` (ON) Always download time zone binaries
+  - Currently, build fails without this
+- `YUZU_TZDB_PATH` (string) Path to a pre-downloaded timezone database (useful for nixOS and Gentoo)
+- `YUZU_USE_BUNDLED_MOLTENVK` (ON, macOS only) Download bundled MoltenVK lib
+- `YUZU_USE_BUNDLED_OPENSSL` (ON for MSVC, Android, Solaris, and OpenBSD) Download bundled OpenSSL build
+- `YUZU_USE_EXTERNAL_SDL2` (OFF) Compiles SDL2 from source
+- `YUZU_USE_BUNDLED_SDL2` (ON for MSVC) Download a prebuilt SDL2
+
+### Miscellaneous
+
+- `ENABLE_WEB_SERVICE` (ON) Enable multiplayer service
+- `ENABLE_WIFI_SCAN` (OFF) Enable WiFi scanning (requires iw on Linux) - experimental
+- `ENABLE_CUBEB` (ON) Enables the cubeb audio backend
+  - This option is subject for removal.
+- `YUZU_TESTS` (ON) Compile tests - requires Catch2
+- `ENABLE_LTO` (OFF) Enable link-time optimization
+  - Not recommended on Windows
+  - UNIX may be better off appending `-flto=thin` to compiler args
+- `USE_FASTER_LINKER` (OFF) Check if a faster linker is available
+  - Not recommended outside of Linux
+
+### Flavors
+
+These options control executables and build flavors.
+
+- `YUZU_LEGACY` (OFF): Apply patches to improve compatibility on some older GPUs at the cost of performance
+- `NIGHTLY_BUILD` (OFF): This is only used by CI. Do not use this unless you're making your own distribution and know what you're doing.
+- `YUZU_STATIC_BUILD` (OFF) Attempt to build using static libraries if possible
+  - Not supported on Linux
+  - Automatically set if `YUZU_USE_BUNDLED_QT` is on for non-Linux
+- `ENABLE_UPDATE_CHECKER` (OFF) Enable update checking functionality
+- `YUZU_DISABLE_LLVM` (OFF) Do not attempt to link to the LLVM demangler
+  - Really only useful for CI or distribution builds
+
+**Desktop only**:
+
+- `YUZU_CMD` (ON) Compile the SDL2 frontend (eden-cli)
+- `YUZU_ROOM` (OFF) Compile dedicated room functionality into the main executable
+- `YUZU_ROOM_STANDALONE` (OFF) Compile a separate executable for room functionality
+- `YUZU_STATIC_ROOM` (OFF) Compile the room executable *only* as a static, portable executable
+  - This is only usable on Alpine Linux.
+
+### Desktop
+
+The following options are desktop only.
+
+- `ENABLE_LIBUSB` (ON) Enable the use of the libusb input frontend (HIGHLY RECOMMENDED)
+- `ENABLE_OPENGL` (ON) Enable the OpenGL graphics frontend
+  - Unavailable on Windows/ARM64
+  - You probably shouldn't turn this off.
+
+### Qt
+
+Also desktop-only, but apply strictly to Qt
+
+- `ENABLE_QT` (ON) Enable the Qt frontend (recommended)
+- `ENABLE_QT_TRANSLATION` (OFF) Enable translations for the Qt frontend
+- `YUZU_USE_BUNDLED_QT` (ON for MSVC) Download bundled Qt binaries
+  - Not recommended on Linux. For Windows and macOS, the provided build is statically linked.
+- `YUZU_QT_MIRROR` (string) What mirror to use for downloading the bundled Qt libraries
+- `YUZU_USE_QT_MULTIMEDIA` (OFF) Use QtMultimedia for camera support
+- `YUZU_USE_QT_WEB_ENGINE` (OFF) Use QtWebEngine for web applet implementation (requires the huge QtWebEngine dependency; not recommended)
+- `USE_DISCORD_PRESENCE` (OFF) Enables Discord Rich Presence (Qt frontend only)
+
+### Retired Options
+
+The following options were a part of Eden at one point, but have since been retired.
+
+- `ENABLE_OPENSSL` - MbedTLS was fully replaced with OpenSSL in [#3606](https://git.eden-emu.dev/eden-emu/eden/pulls/3606), because OpenSSL straight-up performs better.
+- `ENABLE_SDL2` - While technically possible to *not* use SDL2 on desktop, this is **NOT** a supported configuration under any means, and adding this matrix to our build system was not worth the effort.
+- `YUZU_USE_CPM` - This option once had a purpose, but that purpose has long since passed us by. *All* builds use CPMUtil to manage dependencies now.
+  - If you want to *force* the usage of system dependencies, use `-DCPMUTIL_FORCE_SYSTEM=ON`.
+
+See `src/dynarmic/CMakeLists.txt` for additional options--usually, these don't need changed