[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`
Even in this one:

> functions and methods without a return value: the `@return` tag MAY be omitted here, in which case an interpreter MUST interpret this as if `@return void` is provided.

And under [Keyword](https://github.com/phpDocumentor/fig-standards/blob/master/proposed/phpdoc.md#keyword):

> 9 . `void`, this type is commonly only used when defining the return type of a method or function.
>> The basic definition is that the element indicated with this type __does not contain a value__ and the user should not rely on any retrieved value.