[github] Update code owners file (#6420)
[github] Update code owners file (#6420)

# Why

We'd like to have at least two owners of each unimodule, so it will be easier to cooperate in following aspects:
- Bug fixing
- Discussing ongoing changes
- Creating new functionalities
- Code reviewing

# How

- Added some missing packages to the list.
- Added second owner to packages where there is no doubt who should be the owner.
- Put a hyphen to mark orphaned packages.

# Test Plan

Not necessary.

exponentjs/exponent,exponentjs/exponent,exponent/exponent,exponentjs/exponent,exponent/exponent,exponent/exponent,exponent/exponent,exponent/exponent,exponentjs/exponent,exponent/exponent,exponentjs/exponent,exponent/exponent,exponentjs/exponent,exponent/exponent,exponentjs/exponent,exponent/exponent,exponentjs/exponent,exponentjs/exponent