[11.x] Accept non-backed enum in database queries

[gbalduzzi]

This PR aims to implement non backed enums support for database queries, equivalent to the existing support for backed enums implemented in #39492

Non backed enums can be already used as eloquent attribute casting:

enum Status 
{
    case Active;
    case Archive;
}

class User extends Model 
{
  protected $casts = [
    'status' => Status::class,
  ];
}

The enumerative name property is used as the scalar value for Database storage.

$user = new User();
$user->status = Status::Active; // Stored as 'Active' in the database
$user->save();

However, using the enum in the query builder returns an error:

User::where('status', Status::Active)->get(); // ❌ ERROR: Object of class Status could not be converted to string

User::update([ 'status' => Status::Archive]); // ❌ ERROR: Object of class Status could not be converted to string

This PR enables this syntax, automatically casting each non-backed enumerative case to its name.