[Optimization] Lack of interruption function during generation process when uising `TypeSpec VS Code Extension`

**Description:**
When using the `TypeSpec VS Code Extension`, there is a lack of interruption functionality during the generation process. If I mistakenly select an unwanted language or other options, I cannot cancel midway and have to wait for the generation process to complete automatically.


**Repro steps:**

1. Install the typespec extension.
2. Install @typespec/compiler: `npm install -g @typespec/compiler`.
3. Typing `>TypeSpec: Generate from TypeSpec` and Click the command.
4. Choose a project.
5. Select Emitter Type.
6. Select a language, mistakenly select an unwanted language.
7. Have to wait for the generation process to complete automatically.

**Environment:**

- `TypeSpec VS Code Extension` version: 0.64.0
- `TypeSpec compiler/CLI` version: 0.64.0
- OS: Windows, Linux

**Expected behavior:**
Users can interrupt the generation process themselves during the generation.

@RodgeFu, @msyyc and @chunyu3 for notification.