Replace common functionality with rust implementation

mgr/src/cli.rs

@@ -0,0 +1,19 @@
+use thiserror::Error;
+
+#[derive(Error, Debug)]
+pub enum ParseError {
+    #[error("no action given")]
+    MissingAction,
+    #[error("unknown action: {action}")]
+    UnknownAction { action: String },
+    #[error("unexpected input: {rest:?}")]
+    UnexpectedInput { rest: Vec<String> },
+}
+
+pub trait CliCommand {
+    type ExecErr: From<ParseError>;
+
+    fn parse_str(input: &str, rest: impl Iterator<Item = String>) -> Result<Self, ParseError>
+    where
+        Self: Sized;
+}