Drop zend loader, module loader and autoloader provider features.

[Xerkus]

Composer has became a de-facto standard for managing dependencies and autoloading, Zend Framework itself distributes and manages its dependencies via composer. That makes Composer virtually guaranteed to be present for any application.

This PR drops autoloader support in zend-modulemanager in favor of composer autoloader.

This change opens a way for more Module Manager improvements to follow.

[weierophinney]

This repository has been closed and moved to laminas/laminas-modulemanager; a new issue has been opened at https://github.com/laminas/laminas-modulemanager/issues/4.

[weierophinney]

This repository has been moved to laminas/laminas-modulemanager. If you feel that this patch is still relevant, please re-open against that repository, and reference this issue. To re-open, we suggest the following workflow:

• Squash all commits in your branch (git rebase -i origin/{branch})
• Make a note of all changed files (`git diff --name-only origin/{branch}...HEAD
• Run the laminas/laminas-migration tool on the code.
• Clone laminas/laminas-modulemanager to another directory.
• Copy the files from the second bullet point to the clone of laminas/laminas-modulemanager.
• In your clone of laminas/laminas-modulemanager, commit the files, push to your fork, and open the new PR. We will be providing tooling via laminas/laminas-migration soon to help automate the process.