[HooksManager] Show the name of the source for each hook that is run in verbose mode

Closes https://github.com/CocoaPods/CocoaPods/issues/2639.
Closes https://github.com/CocoaPods/CocoaPods/issues/2640.
Closes https://github.com/CocoaPods/CocoaPods/issues/2819.

Depends upon https://github.com/CocoaPods/Core/pull/196.

Huge thanks to @alloy for the `source_location` hint! (feel free to say this all is too gross to include)

- [x] https://github.com/CocoaPods/Core/pull/196
- [x] #2819

\c @kylef would appreciate some help making sure this is a robust solution