feat: create crypto.rs module for generation of tokens

src/crypto.rs

@@ -0,0 +1,14 @@
+use getrandom::fill;
+use hex::encode;
+
+fn generate_access_token() -> Result<String, getrandom::Error> {
+    let mut buf = [0u8; 16];
+    fill(&mut buf)?;
+    Ok(encode(&buf))
+}
+
+fn generate_refresh_token() -> Result<String, getrandom::Error> {
+    let mut buf = [0u8; 32];
+    fill(&mut buf)?;
+    Ok(encode(&buf))
+}