Add subcommand to list local certificates

- Add `husk locals list` to list all certificates which would be used by
  husk, but are not introduced by another certificate. These
  certificates are added 'locally'.
- Refcator the code so that `local` -> `locals`.

src/commands/locals.rs

@@ -0,0 +1,35 @@
+use anyhow::Result;
+
+use crate::cli::cli_args::{LocalsCommand, LocalsSubcommand};
+use crate::common::crypto;
+use crate::config::HuskConfigContainer;
+use crate::types::husk_context::HuskContext;
+
+pub mod add;
+pub mod remove;
+
+pub async fn dispatch(cmd: LocalsCommand, config: HuskConfigContainer) -> Result<()> {
+    match cmd.subcommand {
+        LocalsSubcommand::Add(add_cmd) => {
+            add::dispatch(add_cmd, &config).await?;
+        },
+        LocalsSubcommand::Remove(rm_cmd) => {
+            remove::dispatch(rm_cmd, &config).await?;
+        },
+        LocalsSubcommand::List => {
+            let context = HuskContext::new(&config.into())?;
+
+            println!("list locals");
+            for local in crypto::get_locals(
+                &context.cert_store,
+                &context.policy,
+                context.local_trust_root.fingerprint()) {
+
+                println!("{}", local);
+            }
+
+        },
+    }
+
+    Ok(())
+}