move dump-catalog-shell-cli doc-helper to proxmox-backup-client crate

it's only used for generating the docs for the interactive-shell
parts of the client.

Ideally we'd avoid that whole separate binary in the first place and
let the client dump it, but we'd need to have some more elaborate
"hide this command from the help/usage" mechanisms in the CLI
helper/formatter code to make that play out more nicely.

Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>

proxmox-backup-client/src/bin/dump-catalog-shell-cli.rs

@@ -0,0 +1,20 @@
+use anyhow::{Error};
+
+use proxmox::api::format::*;
+use proxmox::api::cli::*;
+
+use pbs_client::catalog_shell::catalog_shell_cli;
+
+fn main() -> Result<(), Error> {
+
+    match catalog_shell_cli() {
+        CommandLineInterface::Nested(map) => {
+            let usage = generate_nested_usage("", &map, DocumentationFormat::ReST);
+            println!("{}", usage);
+
+        }
+        _ => unreachable!(),
+    }
+
+    Ok(())
+}