feat: implement app commands

refactored to command modules with handler funcs

src/commands/mod.rs

@@ -0,0 +1,19 @@
+pub mod apps;
+pub mod ping;
+
+use std::io::Write;
+
+use crate::cli::{Cli, Command};
+use crate::client::OnspringRunner;
+use crate::error::CliResult;
+
+pub async fn handle<C: OnspringRunner, W: Write>(
+  cli: &Cli,
+  client: &C,
+  writer: &mut W,
+) -> CliResult<()> {
+  match &cli.command {
+    Command::Ping => ping::handle(client, writer, cli.pretty).await,
+    Command::Apps { command } => apps::handle(command, client, writer, cli.pretty).await,
+  }
+}