✨ feat(rules_cli): implement rm_cli subcommand

- add `rm_cli` subcommand structure with clap
- implement basic `run` function for `rm_cli`

src/rules_cli/rm_cli.rs

@@ -0,0 +1,11 @@
+use clap::Parser;
+use cull_gmail::{Config, Error};
+
+#[derive(Debug, Parser)]
+pub struct RmCli {}
+
+impl RmCli {
+    pub fn run(&self, _config: Config) -> Result<(), Error> {
+        Ok(())
+    }
+}