Merge Rust, C and C++ SDKs (#4)

* Generate native bindings from rust crate

* Add native instance and runtime statics

* Update README.md

src/native/models.rs

@@ -0,0 +1,19 @@
+// Copyright (c) Tribufu. All Rights Reserved.
+// SPDX-License-Identifier: MIT
+
+use libc::c_void;
+
+pub struct TribufuApiCallbackContext(pub(crate) *mut c_void);
+
+impl TribufuApiCallbackContext {
+    pub(crate) fn as_ptr(&self) -> *mut c_void {
+        self.0
+    }
+}
+
+unsafe impl Send for TribufuApiCallbackContext {}
+unsafe impl Sync for TribufuApiCallbackContext {}
+
+pub type TribufuApiGetUserInfoCallbackData = c_void;
+pub type TribufuApiGetUserInfoCallback =
+    extern "C" fn(*mut c_void, *const TribufuApiGetUserInfoCallbackData);