Consider having all services in spec repo be under a `.Http` namespace

With the addition of mcp for azure service having the http service taking the `Microsoft.ServiceName` namespace requires any mcp overrides to be under `Microsoft.ServiceNameMcp` ( sibling namesspace) would be nice to have this kind of structure
```
Microsoft.ServiceName.Http
Microsoft.ServiceName.Mcp
```

this also would allow having a `.Client` for exmaple

Review how the existing Microsoft.ServiceName and Microsoft.ServiceNameMcp namespaces are defined for the HTTP and MCP services. Determine the scope of introducing Microsoft.ServiceName.Http and Microsoft.ServiceName.Mcp, including whether a future Microsoft.ServiceName.Client namespace must be accommodated. Done means the namespace structure is agreed and applied consistently across the spec repository.

Written by the indexing model from the issue text.