feat: VS Code extension

[KnorpelSenf]

We may want to have some sort of integration between the docs and the code editor in order to bring even better documentation into the workflow. This is a very hard task (unless someone shows up who has prior experience in creating VSCode extensions) but it may be pretty outstanding in the development experience.

As a starting point, we may want to bundle up the logic of #158 into the extension and display it when the user hovers the cursor over a filter query.

[code-withAshish]

I was wondering about the implementation of the extension if it was to be made as grammy is written primarily in typescript which provides a robust IDE support and autocompletion out of the box.
So what exactly do we mean when we say

We may want to have some sort of integration between the docs and the code editor in order to bring even better documentation into the workflow.

[KnorpelSenf]

That's explained in the next paragraph. For example, filter queries have no tooltip that explains which updates are matched by the respective query. We sometimes get questions regarding the differences between certain filter queries, because people have to derive this from the documentation website. Bringing #158 into the editor solves this.

We will also be able to provide grammY-aware autocomplete that can suggest commonly used code snippets. For example, bot.on could autocomplete to the entire

bot.on("", async (ctx) => {
  // TODO implement handler
})

and place the cursor between the "" and so on.

There might be more ways how the extension could assist you (automatically suggest and install plugins from a UI, project scaffolding, webhook integration generation, maybe even displaying doc pages inline in the editor by passing the Markdown from the repo to the editor's markdown preview so that you don't have to context-switch) but the original description of this issue would likely be a good start before anything else here is implemented.

[KnorpelSenf]

Further things will be tracked in https://github.com/grammyjs/vscode.