- move more sharable code to CI static methods
- merge `release_to_github` and `prepare_next_release` into one single command as they had dependencies on each other
- remove all traces of ruby and fastlane
* Replace ruby/fastlane unit and preview test flows with swift variants.
* Switch to swift-log and Logger for logging
* Address (my own!) PR comments.
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Co-authored-by: Doug <douglase@element.io>