✨ feat(cli): implement label subcommand

- adds label subcommand to manage labels associated with rules
- provides list, add, and remove subcommands for label management

src/config_cli/label_cli.rs

@@ -0,0 +1,40 @@
+use clap::{Parser, Subcommand};
+use cull_gmail::{Config, Error};
+
+mod add_cli;
+mod list_cli;
+mod remove_cli;
+
+use add_cli::AddCli;
+use list_cli::ListCli;
+use remove_cli::RemoveCli;
+
+#[derive(Debug, Subcommand)]
+pub enum LabelCommands {
+    /// List the labels associated with a rule
+    #[clap(name = "list")]
+    List(ListCli),
+    /// Add label to rule
+    #[clap(name = "add")]
+    Add(AddCli),
+    /// Remove a label from a
+    #[clap(name = "remove", alias = "rm")]
+    Remove(RemoveCli),
+}
+
+#[derive(Debug, Parser)]
+pub struct LabelCli {
+    /// Configuration commands
+    #[command(subcommand)]
+    command: LabelCommands,
+}
+
+impl LabelCli {
+    pub fn run(&self, config: Config) -> Result<(), Error> {
+        match &self.command {
+            LabelCommands::List(list_cli) => list_cli.run(config),
+            LabelCommands::Add(add_cli) => add_cli.run(config),
+            LabelCommands::Remove(rm_cli) => rm_cli.run(config),
+        }
+    }
+}