uapi: add support for complete systypes and cargo ecosystem

[pthierry-ledger]

• fix cargo fmt through meson test cargo-fmt
• fix cargo test through meson test cargo-test
• add all missing types in systypes.rs so that Rust app do work properly
• Use CamlCase convesion for Rust types, keeping them separated from the C header's snake case convention

Note: all system types are using repr(C), as the kernel is written in C.