feat: add menu + stage music support

[DarylPinto]

What is this?

In a nutshell, this feature brings music back to Slippi Online. By checking the following box, game music will be restored:

How does it work?

When the checkbox is toggled on, a pair of threads that are completely detached from emulation are spawned. These threads read from game memory to determine which music tracks should be played. When a track should play, a chunk of the iso containing the song is loaded into memory, decoded into audio and played back over the default audio device. No external audio files are used and nothing is ever written to disk.

Features

• Menu music
• All stage music
• Alternate stage music¹
• "Versus" splash screen jingle
• Ranked stage striking music
• Auto-ducking music volume when pausing the game
• Break the Targets + Home Run Contest music
• Controlling volume with the in-game options and Dolphin's audio volume slider
• Lottery menu music
• Single player mode²

1. Alternate stage music has a 12.5% chance of playing. Holding triggers to force alternate tracks to play is not supported.

2. In some 1P modes, stage music will differ from vs mode. This behavior is not supported by jukebox. Additionally, the following songs will not play:

   • Classic "Stage Clear" Jingle
   • Classic "Continue?" and "Game Over" Jingles
   • Credits music
   • Post-credits congratulations fmv music

Limitations

• The WASAPI exclusive audio backend is not currently supported
• Since music is not emulated by Dolphin, there are discrepancies from vanilla - music in the sound test, for example, does not work.

Technical Details

The code that adds music support can be found here:

• https://github.com/ryanmcgrath/Ishiiruka/tree/experimental/rust/Externals/SlippiRustExtensions/jukebox
• https://github.com/DarylPinto/hps_decode

This pull request includes the addition of a Rust submodule, a first for the project. See this comment for details about Rust's integration into Slippi.

[ryanmcgrath]

🐸x 🦀

Just adding on some notes and context to DRL's amazing work to get music back into the game.

In order to facilitate using a Rust lib, I had to make some changes to the Dolphin codebase and build process. A general changelog is below but can expand on anything as needed:

• The Rust codebase is held within Externals/SlippiRustExtensions. It gets built into a dylib that is shipped with the app(s) and linked at runtime, etc.
• Communication between Rust and C++ is done via the C API; the ffi module in Externals/SlippiRustExtensions exposes the "public" API for this. Auto-generated C headers can be found in Externals/SlippiRustExtensions/ffi/includes.
• For platforms that use CMake (macOS, Linux), I updated the CMake build pipeline to use corrosion for building the project. This change is relatively straightforward.
• For Windows, I've updated the Visual Studio solution files to support building the Rust project and including it. This is more custom in nature but I think it works fine, and it's been tested by DRL as well.
• There's now a Rust SlippiEXIDevice that's held by the C++ CEXISlippi class; this is intentional so that the lifecycle on the Rust side meshes well. This is currently blank except for holding the Jukebox, but I figured doing this is useful in case there's a desire to continue doing things in Rust - it provides a sane structure for iterating here.
• AN IMPORTANT CHANGE: in order to get access to certain memory offsets from the Rust side, I've altered the order of Hardware initialization. This moves Memory and ExpansionInterface so that Memory is always around when ExpansionInterface is started or destroyed. This appears to be fine but should be confirmed again in the Mainline move.
• There are changes to the C++ EXI Device to facilitate creating/destroying the Rust EXI Device (mapping to C++ instantiation/destruction) and for toggling the Jukebox.
• The Rust library has support for logging via Dolphin's logging pieces.
  • The Dolphin LogContainer class has been modified to hold its own LogType and to accept a flag marking it as sourcing logs from the Rust library. If that flag is true, a LogContainer will register itself with the Rust side in order to handle ferrying logs across.
  • The Rust side is a custom tracing-subscriber that interops with the above change to dispatch logs to their correct container.
  • There's more complete documentation in the ffi module README on this, as well as how to add new logging containers.
• DRL's Jukebox needs a way to read the current volume from Dolphin, so there's a new AudioCommon GetVolume function that is passed in to the Rust library for the Jukebox to use.
• There's a toggle in the GUI for whether the Jukebox should be enabled or not; this toggle is not there in the Playback builds and the Jukebox itself is not enabled for Playback builds at this time.
• The CI pipeline has been updated to support installing Rust, building and bundling everything together. It will auto-run a check for formatting errors and will run tests in each OS environment, so we can add tests if we find we need them.

(Edit) one more bit of context:

• This PR modifies the CI build to always publish an artifact for macOS runners, even if not signing/notarizing - it will only attempt the signing/notarizing if CI keys exist, otherwise it publishes an unsigned package for testing.

[ryanmcgrath]

(@eigenform may be a good candidate for extra eyes on this with regards to the C++/C/Rust interactions)