Addition of new download scripts and improved .gitignore file

This pull request introduces an update to the .gitignore file and the addition of new utility scripts in the YACHT project.

Key Changes:

.gitignore Refactoring:
- Expanded the .gitignore to include a comprehensive list of Python-related file patterns. This update ensures better project hygiene by preventing unnecessary files (like Python byte-compiled files, C extensions, distribution packages, logs, etc.) from being committed to the repository.
- Removed redundant entries and organized the file for improved readability and maintenance.
New Utility Scripts:
- download_demofiles.py: This script facilitates the automatic downloading of YACHT demo files, enhancing user experience and easing the setup process for new users.
- download_genome_sketches.py: Streamlines the process of downloading genome sketches from specified sources, making it more convenient to gather necessary data for analysis.
- download_pretrained_models.py: Provides an efficient way to download pretrained models from Zenodo, tailored to specific database versions and parameters. This script aids users in quickly setting up their YACHT environment with pre-existing models, significantly reducing setup time.

KoslickiLab / YACHT