Deprecating support for .vscode/mcp.json is a terrible idea

### Describe the bug

I just tried using the CLI and hit this:
[Deprecation of vscode mcp json](https://docs.github.com/en/copilot/reference/copilot-cli-reference/cli-command-reference#migrating-from-vscodemcpjson)

I use that mcp.json all the time in VS code. Now I need two mcp.json files?

### Affected version

_No response_

### Steps to reproduce the behavior

_No response_

### Expected behavior

_No response_

### Additional context

_No response_

Start with the linked migration guidance and review how the CLI currently handles .vscode/mcp.json versus its replacement configuration. Confirm the intended compatibility behavior and identify the relevant configuration discovery and documentation entry points. Done means the issue has a decided, tested approach that avoids requiring duplicate mcp.json files.

索引モデルが issue の本文から書いたものです。