Refactor of `Zend\Db\Metadata` for 3.0.0

[weierophinney]

This is a task for refactoring Zend\Db\Metadata using the type hints of PHP 7.2. You must work on the 3.0.0 branch.

If you change the API you should report it in the /3.0.0.md file.

Note: it's quite difficult to provide this code refactor without changing other classes. That means you should provide the refactoring without pass all the unit tests. In this phase is only important to have the unit tests running, so we you must focus only on fatal/parse errors.

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Originally posted by @ezimuel at zendframework/zend-db#365

[weierophinney]

@ezimuel I have a general question on what the best way it is to handle upcoming questions and issues. While refactoring I had a few questions and mentioned them in the PR comment.

Is this fine or would you prefer a discussion elsewhere, a separate issue, or ...?

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Originally posted by @arueckauer at zendframework/zend-db#365 (comment)

[weierophinney]

This package is considered feature-complete, and is now in security-only maintenance mode, following a decision by the Technical Steering Committee.
If you have a security issue, please follow our security reporting guidelines.
If you wish to take on the role of maintainer, please nominate yourself

If you are looking for an actively maintained package alternative, we recommend:

• doctrine/dbal