Add `ng add` for mcp

### Which @angular/* package(s) are relevant/related to the feature request?

_No response_

### Description

Having https://angular.dev/ai/mcp showcasing what to do is great. Having to configure things manually is not that great. What about having an ng add command which creates those files?

### Proposed solution

`ng add mcp` -> it should ask the user which files it should create

### Alternatives considered

Configure it manually!

Start with the MCP guide at https://angular.dev/ai/mcp and the proposed `ng add mcp` command. Determine which configuration files the command should offer to create and how the prompt should select them; done means the command creates the selected files and supports the documented MCP setup.

Written by the indexing model from the issue text.