Feature: Add the ability to specify how slugs are generated

[RVxLab]

Closes #249 and #275.

This PR adds the ability to specify how slugs are generated. It's mainly targeted to non-Latin alphabet developers who otherwise need to use ASCII characters (or anything that can fit in Str::slug) in order for tabs to work.

Unfortunately, due to a missing Nova 4 license, I'm unable to test this in an application. I did write some unit tests to hopefully cover for this. However, again due to a missing license, I'm unable to properly run those.

Some help will be needed to verify this is working.

[imnpc]

use Chinese test ok on Nova 3 and Nova 4

1.app/Providers/NovaServiceProvider.php

    public function boot()
    {
        parent::boot();
        Tab::createSlugUsing(fn (Tab $tab) => $tab->getTitle()); //  add this line
     }

2.app/Nova/User.php

            Tabs::make('Relations', [
                Tab::make(__('Project'), [
                    HasMany::make('Project')
                ]),
            ]),

OR

            Tabs::make('Relations', [
                Tab::make('项目'), [
                    HasMany::make('Project')
                ]),
            ]),

[RVxLab]

use Chinese test ok on Nova 3 and Nova 4

1.app/Providers/NovaServiceProvider.php

    public function boot()
    {
        parent::boot();
        Tab::createSlugUsing(fn (Tab $tab) => $tab->getTitle()); //  add this line
     }

2.app/Nova/User.php

            Tabs::make('Relations', [
                Tab::make(__('Project'), [
                    HasMany::make('Project')
                ]),
            ]),

OR

            Tabs::make('Relations', [
                Tab::make('项目'), [
                    HasMany::make('Project')
                ]),
            ]),

Thank for your testing this in an application!

@marcfilipan Would you accept this as a testcase?