Merge #1145: Add -h/--help args to the GUI

243f4eac0aaf3def57b3a1107ff8db67749609e7 Add -h/--help args to the GUI (pythcoiner)

Pull request description:

  ```shell
  $ liana-gui -h

  Usage: liana-gui [OPTIONS]

  Options:
      --conf <PATH>       Path of configuration file (gui.toml)
      --datadir <PATH>    Path of liana datadir
      -v, --version       Display liana-gui version
      -h, --help          Print help
      --bitcoin           Use bitcoin network
      --testnet           Use testnet network
      --signet            Use signet network
      --regtest           Use regtest network

  ```

  Closes #1073

ACKs for top commit:
  jp1ac4:
    Tested ACK 243f4eac0aaf3def57b3a1107ff8db67749609e7.

Tree-SHA512: a046966f40da178fd736bcbe0e8042b03fc671baafab71ea3e1413ece3667f915d40f40437c10ecdd27476454d3e552760ac0d2c5d5bc8b21a0b519980cfa9b6

gui/src/main.rs

@@ -44,6 +44,25 @@ fn parse_args(args: Vec<String>) -> Result<Vec<Arg>, Box<dyn Error>> {
         process::exit(1);
     }
 
+    if args.len() > 1 && (args[1] == "--help" || args[1] == "-h") {
+        eprintln!(
+            r#"
+Usage: liana-gui [OPTIONS]
+
+Options:
+    --conf <PATH>       Path of configuration file (gui.toml)
+    --datadir <PATH>    Path of liana datadir
+    -v, --version       Display liana-gui version
+    -h, --help          Print help
+    --bitcoin           Use bitcoin network
+    --testnet           Use testnet network
+    --signet            Use signet network
+    --regtest           Use regtest network
+        "#
+        );
+        process::exit(1);
+    }
+
     for (i, arg) in args.iter().enumerate() {
         if arg == "--conf" {
             if let Some(a) = args.get(i + 1) {