Move current webapp implementation and setup the main branch

[gcroci2]

Move everything that is currently on the main branch to a release_v0.1.0 branch, and initialize properly the main branch for developing the new webapp, something similar to the following:

nplinker-webapp/
│
├── .github/workflows/
│   ├──...
│
├── app/
│   ├── __init__.py
│   ├── layouts.py
│   ├── callbacks.py
│   ├── assets/
│   │   ├── styles.css
│   │   └── custom.js
│   └── components/
│       ├── __init__.py
│       ├── component1.py
│       └── component2.py
│
├── data/
│   └── example_data.csv
│
├── tests/
│   ├── __init__.py
│   ├── test_app.py
│   └── test_components.py
│
├── .gitignore
├── app.py
├── requirements.txt
├── README.md
└── LICENSE

[gcroci2]

The old version of the webapp is now in branch release_v0.1.0