Add support for explicit binding of pattern parameters

[Lukasss93]

This PR adds support for explicit binding of pattern parameters.
This is useful when you want to customize the resolution logic of a pattern parameter.

If you wish to define your own resolution logic for a pattern parameter,
you may use the bindParameter method of the Nutgram class.
The closure you pass to the bindParameter method will receive the value of the parameter and
should return the resolved value that should be injected into the handler.

Before this PR:

$bot = new Nutgram('your-token');

$bot->onCommand('ban {user}', function(Nutgram $bot, string $value){
   $user = User::find($value);
   $user->ban();
});

$bot->run();

After this PR:

$bot = new Nutgram('your-token');

$bot->bindParameter('user', function(string $value){
    return User::find($value);
});

$bot->onCommand('ban {user}', function(Nutgram $bot, ?User $user){
    $user?->ban();
});

$bot->run();

Inspired by https://laravel.com/docs/11.x/routing#customizing-the-resolution-logic

[codeclimate]

Code Climate has analyzed commit 292ac46 and detected 1 issue on this pull request.

Here's the issue category breakdown:

Category	Count
Complexity	1

The test coverage on the diff in this pull request is 100.0% (60% is the threshold).

This pull request will bring the total coverage in the repository to 96.7%.

View more on Code Climate.