Initial devcontainer setup

[thekaveman]

Follow outline in https://github.com/compilerla/template-devcontainer

• Based on Python 3.12
• non-root user
• pre-commit configuration, base on https://github.com/compilerla/template-devcontainer/blob/main/.pre-commit-config.yaml
• .vscode/settings.json with basics for formatting, etc. base on https://github.com/compilerla/template-devcontainer/blob/main/.vscode/settings.json

Post-merge steps

• Activate the pre-commit CI bot for this repo
• Make the associated check a required check in the protection rules