`add-ns` doesn't exclude web-only components from mobile tsconfig

Initally, when adding nativescript to a web project, all components are web-only. They should be excluded from the mobile AoT build. For example:
https://github.com/sis0k0/routing-web-mobile/blob/25579ed90439373c418557a65f057fdbf88ad3cc/tsconfig.aot.json#L19

Also, the `migrate-component` schematic should remove the migrated component from the list of excluded files.