新增rust ffi (#77)

* 引入cargo

* 取消对Cargo.lock的跟踪

* 解决vscode报错问题

* new: rust的代码能够调用c语言的printk_color

* 1、将原本run.sh的工作拆解，变为几个不同的make命令
2、在docker镜像中编译rust

* 更改workflow

* update workflow

* new: 解决workflow无法通过编译的问题

kernel/src/lib.rs

@@ -0,0 +1,26 @@
+#![no_std]                       // <1>
+#![no_main]                      // <1>
+#![feature(core_intrinsics)]     // <2>
+#[allow(non_upper_case_globals)]
+#[allow(non_camel_case_types)]
+#[allow(non_snake_case)]
+
+use core::ffi::c_char;
+use core::intrinsics;            // <2>
+use core::panic::PanicInfo;      // <3>
+include!("include/bindings/bindings.rs");
+
+#[panic_handler]
+#[no_mangle]
+pub fn panic(_info: &PanicInfo) -> ! {
+  intrinsics::abort();           // <4>
+}
+
+#[no_mangle]
+pub extern "C" fn __rust_demo_func() -> i32 {
+  unsafe{
+    let f = b"\nDragonOS's Rust lib called printk_color()\n".as_ptr() as *const c_char;
+    printk_color(GREEN, BLACK, f);
+  }
+  return 0;
+}