Testing: Add publish tests using the block editor

[rachelmcr]

This PR adds a new Gutenberg test suite with two publish flow tests using the block editor. These are the same publish tests we already had running for Aztec (which are now in a single Aztec test suite).

This PR also switches the main navigation test to use the block editor instead of Aztec. (The navigation itself is the same, but we have to define which editor we expect to open after tapping the editor button in the bottom nav bar.)

Note: For now, the block editor tests only run in English. We'll need to look at either adding test IDs to Gutenberg or making the localizable strings from Gutenberg accessible to these tests (less stable) to run them in other device languages.

To test:

• Pull the latest mobile secrets, or create a file with test credentials at ~/.mobile-secrets/iOS/WPiOS/WPUITestCredentials.swift (based on the template at /WordPressUITests/WPUITestCredentials-Template.swift).
• Open the simulator and confirm the device language is set to Ennglish.
• Run the all test suites except LoginTests in the WordPressUITests target.

Update release notes:

• If there are user facing changes, I have added an item to RELEASE-NOTES.txt.

[JavonDavis]

The code LGTM! and the tests work pretty well! 👍🏽 I just have a small nitpick and a case I think we should cover..

There's something I noticed when I was initially testing this out, running the Gutenberg tests before the Aztec tests led to a failure as a result of the block editor still being on... I cleaned the build folder and went again and now I noticed that each time the app was being reinstalled so this couldn't be reproduced anymore(weird but I don't think that's the expected behavior). To reproduce this a simple change of EditorGutenbergTests to EditorAGutenbergTests can do the trick... I know in the current scenario unless the tests are ran separately this shouldn't happen or but I think this can also occur if the app isn't re-installed and the BlockEditor is still on.. I'm thinking we can just always ensure the block editor is off for the AztecEditor test in a similar approach to what's being done in the BlockEditor test...

The nitpick I had is that we're using

        super.setUp()
        // In UI tests it is usually best to stop immediately when a failure occurs.
        continueAfterFailure = false

        let app = XCUIApplication()
        app.launchArguments = ["NoAnimations"]
        app.activate()

        // Media permissions alert handler
        systemAlertHandler(alertTitle: "“WordPress” Would Like to Access Your Photos", alertButton: "OK")

in the setUp for most of the tests and probably will use it in future tests as well, any chance we could reuse that block of code in a function?

[rachelmcr]

I'm thinking we can just always ensure the block editor is off for the AztecEditor test in a similar approach to what's being done in the BlockEditor test...

Good call, that's an easy thing to add. 👍

The nitpick I had is that we're using [...] in the setUp for most of the tests and probably will use it in future tests as well, any chance we could reuse that block of code in a function?

Yeah, I hadn't thought about that. I'll take a look at what makes the most sense there for reusing all or most of that block of code. Thanks!

[peril-wordpress-mobile]

	Warnings
⚠️	PR has more than 500 lines of code changing. Consider splitting into smaller PRs if possible.

Generated by 🚫 dangerJS

[JavonDavis]

LGTM! 🚢