feat: move connect to pkg namespace

[VictorAvelar]

Description

Moves the connect package to the pkg namespace.

Motivation and context

Consistency for the library by keeping all the side packages in the correct namespace and leaving only the core library at the mollie directory.

Types of changes

What types of changes does your code introduce? Put an x in all the boxes that apply:

• [ ] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [x] Breaking change (fix or feature that would cause existing functionality to change)
• [ ] This change requires a documentation update

Checklist

Go over all the following points, and put an x in all the boxes that apply.

Please, please, please, don't send your pull request until all of the boxes are ticked. Once your pull request is created, it will trigger a build on our continuous integration server to make sure your tests and code style pass.

• [x] I have read the CONTRIBUTING document.
• [x] My pull request addresses exactly one patch/feature.
• [x] I have created a branch for this patch/feature.
• [x] Each individual commit in the pull request is meaningful.
• [x] If my change requires a change to the documentation, I have updated it accordingly.