Add comprehensive instruction files for GitHub Copilot and project guidelines

- Create copilot-instructions.md with core directives, interaction philosophy, and development patterns for MaveDB API.
- Establish instructions.instructions.md for creating high-quality custom instruction files for GitHub Copilot.
- Introduce markdown.instructions.md outlining documentation and content creation standards.
- Develop prompt.instructions.md detailing guidelines for crafting effective prompt files for GitHub Copilot.
- Implement python.instructions.md to specify Python coding conventions and guidelines.
- Add prompt-builder.prompt.md to guide users in creating structured and effective GitHub Copilot prompts.

Included files are inspired by or from the prompt and instructions files available at https://github.com/github/awesome-copilot/blob/main

Author: bencap