[Feature] Development ready testing environment

[quank123wip]

Initial checklist

• [X] I agree to follow the code of conduct
• [X] I searched issues and discussions and couldn’t find anything (or linked relevant results below)

Problem

As milkdown has rich support for plugins and themes, maybe provide a official easy-to-config, easy-to-fetch, easy-to-moddify environment contains necessary packages and configs for developers testing their plugins and themes.

Solution

Just start from milkdown/e2e, create a template project for developers to begin on.

Alternatives

For now, people can make their own development environment with vite or something else on the basis of e2e.

[Saul-Mirone]

I'm working on crepe. Is this something what you want?

[quank123wip]

I'm working on crepe. Is this something what you want?

Not quite, crepe makes this easier, but imo we need a template repository to let developers start faster. Maybe we just need to publish a repository shipped with crepe and other configs.