New package architecture to enable pip install pytwin

[lboucin]

What this PR does?

This PR reworks the package architecture to enable user to do:

• pip install pytwin and
• from pytwin.evaluate import TwinModel.

Also formats all doc string to pyaedt compliant style.

@chrpetre please note that you will have to recreate a poetry virtual environment after this PR will be merged.

Type(s) of change

• Non-functional changes (e.g. code styling, development documentation, policy-related and etc.)
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

How Has This Been Tested?

• New unit tests added
• Current unit tests passed
• Existing unit tests updated
• Manual/interactive tested

[lboucin]

@MaxJPRey FYI.