Adding scannet download methods and configs

[jaswanthbjk]

What does this PR do?

Adding ScanNet dataloader to the library

Fixes #35

Before submitting

• [x] Did you make sure title is self-explanatory and the description concisely explains the PR?
• [x] Did you make sure your PR does only one thing, instead of bundling different changes together?
• [x] Did you list all the breaking changes introduced by this pull request?
• [ ] Did you test your PR locally with pytest command?
• [ ] Did you run pre-commit hooks with pre-commit run -a command?

Did you have fun?

Make sure you had fun coding 🙃