refac(cli): move opts to separate file

migra-cli/src/main.rs

@@ -1,12 +1,8 @@
 #![deny(clippy::all)]
 
-use structopt::StructOpt;
-
-#[derive(Debug, StructOpt)]
-enum AppOpt {
-    Init,
-}
+mod opts;
 
+use opts::{AppOpt, StructOpt};
 
 fn main() {
     let opt = AppOpt::from_args();

migra-cli/src/opts.rs

@@ -0,0 +1,6 @@
+pub use structopt::StructOpt;
+
+#[derive(Debug, StructOpt)]
+pub(crate) enum AppOpt {
+    Init,
+}