Standalone flipper-zero plugins in embedded rust

This repo demonstrates compiling a flipper-zero app in rust, then using unholy linker incantations to smooze it into an elf file that fz can load.

This is terrible dont use this.

1. Rust crate uses the amazing flipper-zero crates by dcoles, compiling to an intermediate .a with a fixed plugin_start identifier for the entrypoint.
2. (build.sh) Unholy invocation of gcc to compile the rustc-generated archive to an ELF the fz can work with.
3. (gen_fapmeta.py) Generates the weird .fapmeta ELF section that tells the loader about what SDK version its compiled against as well as the app name and other crap.
4. (build.sh) objcopy incantation to strip binary bloat and weave in the generated fapmeta section.

Assuming a NixOS system:

nix-shell
./build.sh
# The binary should now be in target/thumbv7em-none-eabihf/release/libfz_rust.fap

Look, do whatever lol. The bits I copied from the flipperzero sauce are licensed GNUv3 and marked appropriately. The bits i copied from dcoles are MIT and marked appropriately. Everything else, lets just say its dual GNUv3 & MIT.

Mad props to dcoles for making the crates for binding to the SDK, as well as the example code I copypasta'd. The only novel bit in this repo is building a fap file without needing a copy of the firmware and a working firmware toolchain.