MCP template should use token replacement for id in server.json

### Description

In the `.mcp/server.json` there is an identifier that has a placeholder `` -- this really should use the sourceName property of the template which would get the automatic replacement value and mirror what is used in the `PackageId` in the csproj.

Changing `` to `McpServer-CSharp` will do the trick as that is the sourceName -- `PackageId` should be changed too.

### Reproduction Steps

Create a new project with the template named "TimFooBar"

### Expected behavior

PackageId defaults to the project name. This is common templating behavior.

### Actual behavior

Hard-coded to SampleMcpServer

### Regression?

No

### Known Workarounds

Manually change it

### Configuration

_No response_

### Other information

_No response_