refactor: remove the *.xcodeproj from ios template (#470)

### Summary

This removes the `*.xcodeproj` from the `ios` directory in the generated
library. These files are not needed for autolinking, and keeping them
has few downsides:

- People open this project instead of example and it doesn't work, so it
adds confusion
- It's a big unreadable file to maintain, both for library developers
and for us

### Test plan

Generate a project without the `*.xcodeproj` and verify that it compiles
and runs

Author: satya164