Add "Installation" page to main documentation

[musslick]

We should include a guide to installing autora in ones' local environment. The guide should include:

• [x] List of supported python versions
• [x] Basic pip/conda install instruction
• [x] Introduction to packaging structure optional dependencies, which could build on this: https://autoresearch.github.io/autora/contribute/#project-structure
• [x] Example for optional package installations with pip/conda
• [x] A (curated) list of all available vetted (optional) autora pip/conda packages along with a link to their respective page in the documentation. Perhaps this could be a table?
• [ ] We should also consider adding the name of the autora pip/conda package for each tool in the main doc file (index.md) of the respectvie package.