Fix issue of type i64 in Rust not properly getting converted to BigInt in TypeScript (#858)

* Fix issue of type i64 / u64  in Rust not properly getting converted to BigInt in TypeScript

Author: Kev

capi/bind_gen/src/wasm_bindgen.rs

@@ -27,11 +27,11 @@ fn get_hl_type_without_null(ty: &Type) -> String {
                 "i8" => "number",
                 "i16" => "number",
                 "i32" => "number",
-                "i64" => "number",
+                "i64" => "BigInt",
                 "u8" => "number",
                 "u16" => "number",
                 "u32" => "number",
-                "u64" => "number",
+                "u64" => "BigInt",
                 "usize" => "number",
                 "isize" => "number",
                 "f32" => "number",