2-factor improvements

* Improve support for 2-factor and 2-step verification a lot ((#7738)
* Add support for application specific passwords using environment variables (#7738)
* Improved wording and documentation for 2-factor and 2-step (#7738)
* Update checker ensures valid RubyGems source for fastlane updates (#7734)
* Print fastlane path when running `fastlane -v` (#7733)
* Fix crash in _deliver_ when using the new `live` option (#7726)
* Fix USB device discovery to account for USB hubs (#7727)
* Fix USB data parsing problem for DeviceManager (#7725)
* Skip installing plugins when running `fastlane -v` (#7722)
* Add support for uploading proguard mapping files (#7721)

https://github.com/fastlane/fastlane/releases/tag/2.5.0
