Automatic completion, renaming, go to define based on decorator parameters

まだ誰も着手していません。

### 🔍 Search Terms

language server, decorator, auto completions

### ✅ Viability Checklist

- [x] This wouldn't be a breaking change in existing TypeScript/JavaScript code
- [x] This wouldn't change the runtime behavior of existing JavaScript code
- [x] This could be implemented without emitting different JS based on the types of the expressions
- [x] This isn't a runtime feature (e.g. library functionality, non-ECMAScript syntax with JavaScript output, new syntax sugar for JS, etc.)
- [x] This isn't a request to add a new utility type: https://github.com/microsoft/TypeScript/wiki/No-New-Utility-Types
- [x] This feature would agree with the rest of our Design Goals: https://github.com/Microsoft/TypeScript/wiki/TypeScript-Design-Goals

### ⭐ Suggestion

In the following example, when no function return type is specified, the decorator parameter type should be automatically completed, renamed, and go to define.


### 📃 Motivating Example

This makes it easier to write when applying decorator

### 💻 Use Cases

[playground](https://www.typescriptlang.org/play/?#code/GYVwdgxgLglg9mABAEwKYTgJwIZS4gCgDcAuRbMATwBpFoAPMgYQBtsBndgWVSgAs4yACLosuLEwRRU9KAB4KNQgEpEAXgB8iAN6JgMVC2Rl2UTDDABzRAF8Nq7QFgAUC5suXoSLAQpROPEwARkJScipaBmY2TgAxAyMRDACJKRl5RVoCVU0dPQTjRFNzK1t7HQ9nd1dnCBj2RABBCudERAABNGTxTBc26VNslra2zF4QTCRdfUNCgHI52z6lmrbO-x6g5YGoELUVdS0nVpGxqAmp-NmyBZW26psgA)

リンクされた TypeScript Playground の例から始め、そこで decorator parameter のシナリオを再現してください。関数の戻り値の型が省略されている場合に、language service が現在 completion、rename、go-to-definition をどのように処理しているかを追跡してください。decorator parameter に対して3つすべての操作が、生成される JavaScript を変更せずに機能すれば完了です。

索引モデルが issue の本文から書いたものです。