docs: add scaffolding for testcontainers docs system

[mdelapenya]

What does this PR do?

It adds the base Mkdocs project for the testcontainers docs system.

It uses tc-go as reference, removing all the go-specific content but the general one.

Why is it important?

Homogeneous and consistent docs system across testcontainers projects.

How to test this PR

As described in the docs/contributing_docs.md file in this PR:

• Ensure that you have Python 3.8.0 or higher.
• Create a Python virtualenv. E.g. python3 -m venv tc-venv.
• Activate the virtualenv. E.g. source tc-venv/bin/activate.
• Run pip3 install -r requirements.txt && ./tc-venv/bin/mkdocs serve from the testcontainers-rs root directory. It will start a local auto-updating MkDocs server.

Follow-ups

• Add features
• Add modules
• Create rust.testcontainers.org domain
• Enable netlify deployments and previews in PRs

[mdelapenya]

As a follow-up I'd like to to simplify the experience, as in testcontainers/testcontainers-go#2545

[DDtKey]

Thank you 🙏