firebase-ios-sdk

Move zip-builder to ArgumentParser. (#6920)

* Move zip-builder to ArgumentParser.

This provides more consistency with the other tooling, and lays
groundwork to make further changes to arguments passed in.

* Update zip build workflow, enable temporarily.

* Fix typo in build script.

* Removed RC option + other review feedback

* Style

* Fix Carthage naming.

* Revert V2 plan doc, add V3 plan

* Remove trailing space.

* Update some missed parts, fix zip builds.

* Removed old references in README.

* Fixed trailing whitespace.

* Revert GHA cron run.

* Review