Improve migration from zend-servicemanager-di

[weierophinney]

From PR #35

ZF is aiming to allow easy migrations to new component versions whenever possible. For zend-di there is a component that integrated version 2 into zend-servicemanager.
Version 3 introduced a conflict-entry in it's composer.json, that states clearly zend-servicemanager-di is no longer needed. But it will also urge consumers to potentially upgrade many parts of their application.

To make life easier for these users, we should provide a new version for zend-servicemanager-di, that will deprecate it's own usage but allowing the user's to remove it's parts step by step.

Link to the discourse topic

This issue should keep track of this topic after migration to Laminas is complete.

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Originally posted by @tux-rampage at zendframework/zend-di#58