Add library with Rust bindings to target_f1 code (#68)

* Move flipper-core into a workspace

* Fix target build rules

* Add flipper-f1-sys library

* Add flipper-f1-sys dependency to flipper-core

* Remove apparently useless includes

* Build and export HAL statics

* Disable Rust dependency detection for target_f1 build

* Install libclang-10-dev in docker

* Build Rust libs every time

* remove duplicate sources from make

* clean build different example

* wip add example fn

* Implement rust_uart_write()

* fix rebuild instructions for target_f1

Co-authored-by: aanper <mail@s3f.ru>

core-rs/flipper-core/src/lib.rs

@@ -0,0 +1,39 @@
+#![no_std]
+
+#[cfg(target_arch = "arm")]
+use flipper_f1_sys::hal::{HAL_UART_Transmit_IT, huart1};
+
+#[no_mangle]
+pub extern "C" fn add(a: u32, b: u32) -> u32 {
+    a + b
+}
+
+
+#[no_mangle]
+pub extern "C" fn rust_uart_write() {
+    let string = "Rust test string\n";
+    let bytes = string.as_bytes();
+
+    #[cfg(target_arch = "arm")]
+    unsafe {
+        HAL_UART_Transmit_IT(&mut huart1, bytes.as_ptr() as *mut _, bytes.len() as u16);
+    }
+    #[cfg(not(target_arch = "arm"))]
+    unsafe {
+        extern "C" {
+            fn write(handle: i32, ptr: *const u8, size: usize) -> isize;
+        }
+
+        write(1, bytes.as_ptr(), bytes.len());
+    }
+}
+
+
+mod aux {
+    use core::panic::PanicInfo;
+
+    #[panic_handler]
+    fn panic(_info: &PanicInfo) -> ! {
+        loop { continue }
+    }
+}