Exclude deprecated commands from completions (#9612)

# Description
We previously simply searched all commands in the working set. As our
deprecated/removed subcommands are documented by stub commands that
don't do anything apart from providing a message, they were still
included.
With this change we check the `Signature.category` to not be
`Category::Deprecated`.

## Note on performance
Making this change will exercise `Command.signature()` more
frequently! As the rust-implemented commands include their builders here
this probably will cause a number of extra allocations. There is
actually no valid reason why the commands should construct a new
`Signature` for each call to `Command.signature()`.
This will introduce some overhead to generate the completions for
commands.
# User-Facing Changes
Example: `str <TAB>`


![grafik](https://github.com/nushell/nushell/assets/15833959/4d5ec5fe-aa93-45af-aa60-3854a20fcb04)

crates/nu-cli/src/completions/command_completions.rs

@@ -89,7 +89,7 @@ impl CommandCompletion {
         let filter_predicate = |command: &[u8]| match_algorithm.matches_u8(command, partial);
 
         let mut results = working_set
-            .find_commands_by_predicate(filter_predicate)
+            .find_commands_by_predicate(filter_predicate, true)
             .into_iter()
             .map(move |x| Suggestion {
                 value: String::from_utf8_lossy(&x.0).to_string(),