feat: Adding new --format option in routes CLI command for JSON format (#4417)

[MauricioReisdoefer]

Description

This PR introduces a --format option for the litestar routes CLI command, allowing routes to be output in a structured JSON format. This is useful for automation, scripts, or integration with external tools.

Usage Example

Example usage:

```bash
$ litestar routes --format=json
[
  {
    "name": h.name,
    "path": h.paths,
    "handler": h.handler_name,
    "methods": sorted(h.http_methods),
    "async": inspect.iscoroutinefunction(unwrap_partial(h.fn))  
  },
]

Motivation and Context

Closing issue #4417. This change allows developers to easily consume route information programmatically, improving automation and tooling support.

Also i added new tests to cover this new feature.

Closes

[provinzkraut]

It would be better to add a --format option, with json as a choice, as that is more extendable.

[MauricioReisdoefer]

I agree. But first i'll fix the unpassed tests.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 97.83%. Comparing base (d87e20f) to head (c869c2d).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4418      +/-   ##
==========================================
- Coverage   97.83%   97.83%   -0.01%     
==========================================
  Files         296      296              
  Lines       15295    15317      +22     
  Branches     1713     1718       +5     
==========================================
+ Hits        14964    14985      +21     
  Misses        189      189              
- Partials      142      143       +1     

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[provinzkraut]

@MauricioReisdoefer if you want to get this merged, please address the changes I've requested regarding the flag.

[MauricioReisdoefer]

Do you want any more changes in this pr? Like, creating a new format already? Because i want to start contributing in other parts after this pr.

[github-actions]

Documentation preview will be available shortly at https://litestar-org.github.io/litestar-docs-preview/4418