feat: add a command_not_found hook (#8314)

# Description
Add a `command_not_found` function to `$env.config.hooks`. If this
function outputs a string, then it's included in the `help`.

An example hook on *Arch Linux*, to find packages that contain the
binary, looks like:

```nushell
let-env config = {
  # ...
  hooks: {
    command_not_found: {
      |cmd_name| (
        try {
          let pkgs = (pkgfile --binaries --verbose $cmd_name)
          (
            $"(ansi $env.config.color_config.shape_external)($cmd_name)(ansi reset) " +
            $"may be found in the following packages:\n($pkgs)"
          )
        } catch {
          null
        }
      )
    }
    # ...
```

# User-Facing Changes
- Add a `command_not_found` function to `$env.config.hooks`.

# Tests + Formatting

Don't forget to add tests that cover your changes.

Make sure you've run and fixed any issues with these commands:

- `cargo fmt --all -- --check` to check standard code formatting (`cargo
fmt --all` applies these changes)
- `cargo clippy --workspace -- -D warnings -D clippy::unwrap_used -A
clippy::needless_collect` to check that you're using the standard code
style
- `cargo test --workspace` to check that all tests pass

# After Submitting

If your PR had any user-facing changes, update [the
documentation](https://github.com/nushell/nushell.github.io) after the
PR is merged, if necessary. This will help us keep the docs up to date.

src/command.rs

@@ -1,4 +1,4 @@
-use nu_cli::report_error;
+use nu_command::util::report_error;
 use nu_engine::{get_full_help, CallExt};
 use nu_parser::parse;
 use nu_parser::{escape_for_script_arg, escape_quote_string};

src/config_files.rs

@@ -1,7 +1,8 @@
 use log::info;
 #[cfg(feature = "plugin")]
 use nu_cli::read_plugin_file;
-use nu_cli::{eval_config_contents, eval_source, report_error};
+use nu_cli::{eval_config_contents, eval_source};
+use nu_command::util::report_error;
 use nu_parser::ParseError;
 use nu_path::canonicalize_with;
 use nu_protocol::engine::{EngineState, Stack, StateWorkingSet};

src/main.rs

@@ -17,8 +17,9 @@ use crate::{
 use command::gather_commandline_args;
 use log::Level;
 use miette::Result;
-use nu_cli::{gather_parent_env_vars, get_init_cwd, report_error_new};
-use nu_command::create_default_context;
+use nu_cli::gather_parent_env_vars;
+use nu_command::util::report_error_new;
+use nu_command::{create_default_context, get_init_cwd};
 use nu_protocol::{util::BufferedReader, PipelineData, RawStream};
 use nu_utils::utils::perf;
 use run::{run_commands, run_file, run_repl};

src/test_bins.rs

@@ -1,7 +1,7 @@
 use std::io::{self, BufRead, Read, Write};
 
-use nu_cli::{eval_env_change_hook, eval_hook};
 use nu_command::create_default_context;
+use nu_command::hook::{eval_env_change_hook, eval_hook};
 use nu_engine::eval_block;
 use nu_parser::parse;
 use nu_protocol::engine::{EngineState, Stack, StateWorkingSet};