Allow user to change default installation location for components/screens

Allow the `nwui-cli` install components to a custom path like `./src/components`  instead of the default `./components`. 

Expo Router supports both `./app/` and `./src/app/`. It would be nice if `nwui-cli` did as well.  As a followup, what about installing components to a monorepo packages, like ./packages/ui/src?

Perhaps this could be done via a path flag.