Update screenshot test with new mocks

[rachelmcr]

Updates the screenshot test with new mock data for new app store screenshots.

Notable changes:

• Depends on Remove localization from accessibility IDs WordPressAuthenticator-iOS#493 to support running the tests in any language.
• Depends on Update screenshot mocks WordPressMocks#20 for the new mocks.
• Adds a new accessibility ID to the comment notification reply button.
• Makes some updates to the screenshot test to support the new mocked data (e.g. switching sites).
• Makes some updates to the UI tests and screen objects to support the new mocked data.

Note: We're aiming to use the new screenshots with the 15.9 release, but I'm targeting develop because we don't expect any significant UI differences between the release/15.9 and develop branches.

Screenshots

Sample iPad screenshots:

Editor	Reader	My Site/Stats	Notifications	Editor with keyboard	Media

Sample iPhone screenshots:

Editor	Reader	Stats	My Site	Notifications	Media

To test:

• Confirm all the regular UI tests pass (WordPressUITests) on this PR.
• Confirm the WordPressScreenshotGeneration tests produces the expected screenshots:
  • Run rake mocks to start the mock server.
  • Open the fastlane directory with cd Scripts/fastlane.
  • Generate a set of screenshots: bundle exec fastlane screenshots for a full set in all languages (this takes a while) or e.g. bundle exec fastlane screenshots language:"es-ES" for a set of screenshots in a single non-English language to confirm it works for all targeted devices regardless of language.

Before merge

• Update the Podfile/Podfile.lock to use to the published WordPressAuthenticator and WordPressMocks pods (once those PRs are merged).

PR submission checklist:

• I have considered adding unit tests where possible.
• I have considered adding accessibility improvements for my changes.
• I have considered if this change warrants user-facing release notes and have added them to RELEASE-NOTES.txt if necessary.

[peril-wordpress-mobile]

You can trigger an installable build for these changes by visiting CircleCI here.

[peril-wordpress-mobile]

You can trigger optional UI/connected tests for these changes by visiting CircleCI here.

[startuptester]

@rachelmcr, the first thing I ran across was that the image from the Editor screenshot is missing

[startuptester]

• The UI tests pass
• Script runs and screenshots are correct except for the missing image in the dog grooming page

[rachelmcr]

the image from the Editor screenshot is missing

We currently don't mock the requests for media files, so likely the file wasn't loaded fast enough during your run.

I confirmed that it loaded and appeared in the screenshots when I generated them. Since it worked well on my end I thought we wouldn't need anything extra for that screenshot, but to avoid that flakiness I've added sleep(imagesWaitTime) before both of the editor screenshots to make sure the images have time to load.

I still need to resolve the Podfile.lock conflict, but I also need to update the two pod references that this PR depends on, so I'll plan to take care of that once those PRs are merged and the new pods are available.

[rachelmcr]

@startuptester Ok, pods are updated, conflicts resolved, and this is ready for another review!

[startuptester]

Ran script again in Spanish after merging of the two associated PRs. Ran without error and screenshots look good!
💯