refactor(@angular/cli): remove modernize tool and add instructions for schematic discovery

Remove the `modernize` tool from the Angular CLI MCP server, as it is largely redundant with the
official Angular developer skill and direct usage of schematics. To compensate for this removal,
add instructions to the server describing how agents can use `ng generate <package>: --help` to
discover available modernization schematics. This simplifies the codebase while maintaining the
ability for agents to perform code modernization.