Adds support for SageMath in the Zed text editor.

The Tree Sitter Grammar is provided by Håvard Damm-Johnsen.

In the future I hope to add a language server: exploring if rewriting the Sage-specific expressions to Python (or simply using the Sage compiled) together with a Python language server is feasible.

If you would like to contribute, please open an issue to discuss or pull request.

All contributions must be made under the MIT License.