Refactor(eos_designs): Move eos_designs_shared_utils to PyAVD

[ClausHolbechArista]

Change Summary

Move internal code in eos_designs_shared_utils to PyAVD

Proposed changes

• Move files and update all imports
• Fix issues caught by Pylint

How to test

• No changes to molecule or pytest. Yay!

Checklist

User Checklist

• N/A

Repository Checklist

• My code has been rebased from devel before I start
• I have read the CONTRIBUTING document.
• My change requires a change to the documentation and documentation have been updated accordingly.
• I have updated molecule CI testing accordingly. (check the box if not applicable)

[github-actions]

Review docs on Read the Docs

To test this pull request:

# Create virtual environment for this testing below the current directory
python -m venv test-avd-pr-4126
# Activate the virtual environment
source test-avd-pr-4126/bin/activate
# Install all requirements including PyAVD
pip install "pyavd[ansible] @ git+https://github.com/ClausHolbechArista/avd.git@refactor/eos_designs/move-eos_designs_shared_utils-to-pyavd#subdirectory=python-avd" --force
# Install Ansible collection
ansible-galaxy collection install git+https://github.com/ClausHolbechArista/avd.git#/ansible_collections/arista/avd/,refactor/eos_designs/move-eos_designs_shared_utils-to-pyavd --force
# Optional: Install AVD examples
cd test-avd-pr-4126
ansible-playbook arista.avd.install_examples

[carlbuchmann]

LGTM

[gmuloc]

LGTM once CI passes