[10.x] Add ScopedBy attribute for models

[emargareten]

This PR is similar to my previous PR, but for global scopes. It adds an option to register global scopes via an attribute.

For example:

#[ScopedBy(AncientScope::class)]
class User extends Model
{
    //
}

It's also possible to use an array of scope classes:

#[ScopedBy([FirstScope::class, SecondScope::class])]

This makes it easier to see which global scopes are applied to a model rather than having to look through the boot method.