[Optimization] Specify the path to the generated code when Generate from TypeSpec

[xiaohua899]

Description:

When Generate from TypeSpec, users cannot specify the path for code generation in the UI interface, and there is no documentation explaining how to change the code generation path in the tspconfig.yaml file.

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.
7. Select an emitter for code generation.

Environment:

• TypeSpec for VS Code extension version: 0.64.0
• TypeSpec compiler/CLI version: 0.64.0
• OS: Windows, Linux

Suggestion:

Choose one of the following two suggestions:

1. After select the emitter type and language, can add a step to interact with the UI interface of select the path for code generation, the default is the project path.
2. There is a document explaining how to modify the code generation path in the tspconfig.yaml file.

@RodgeFu , @chunyu3 and @msyyc for notification.