[5.0] Extracted Contracts

Extracted Database, View, Validation, Translation and Queue contracts.

Fixed some typos along the way

Only ones remaining are:
* `Illuminate\Routing\Annotations\EndpointInterface`
* `Illuminate\Routing\Matching\ValidatorInterface`
Is this better?
```php
// Next we will register the various engines with the resolver
// so that the environment can resolve the engines it needs
// for various views based on the extension of view files.
// We call a method for each engines.
```