Allow CircleCI to generate new test snapshots

[joshdholtz]

Depends on https://github.com/RevenueCat/purchases-ios/pull/1589

Motivation

Our snapshot testing sometimes needs regeneration and it requires regeneration of iOS 12. iOS 12 simulators only run on Intel machines and not all of us have them.

This PR will allow a CircleCI job to be manually triggered to regenerate snapshot tests

Description

Step 1: Trigger CircleCI workflow

Run bundle exec fastlane generate_snapshots

Step 2: Run CircleCI workflow with generate snapshots

This will start a series of jobs on CircleCI that will have the CIRCLECI_TESTS_GENERATE_SNAPSHOTS set to true that will regenerate new/updated snapshot test assets.

Step 3: Create pull requests

If there are any files changed, a new PR will be created against the base branch (set earlier in the generate_snapshots lane)

Example PR 👉 https://github.com/RevenueCat/purchases-ios/pull/1578

[joshdholtz]

@NachoSoto Pushed a commit where no Xcode formatter (raw output) will be used when generating snapshots!

[NachoSoto]

Looks like this is working 🎉

But let's run it against #1560 to see if it generates the new ones correctly too.

[aboedo]

what's the status of this one?

[NachoSoto]

Should we close this for now?

[joshdholtz]

Ahhh... this one was super frustrating! CircleCI wasn't generating the things properly even though it should have. Probably should close it 😬

[NachoSoto]

We can pair to finish it, I'm sure it's almost ready?

[joshdholtz]

I'd be down to pair sometime 😊

[NachoSoto]

Closing in favor of #2472.