[snapshot] Fix compatibility with macOS

[ptrkstr]

Checklist

• I've run bundle exec rspec from the root directory to see all new and existing tests pass
• I've followed the fastlane code style and run bundle exec rubocop -a to ensure the code style is valid
• I've read the Contribution Guidelines
• I've updated the documentation if necessary.

Motivation and Context

Why is this change required? What problem does it solve?

• Snapshot targets that target macOS would fail to build when including SnapshotHelper.swift because it contained symbols not available on macOS. This PR solves that problem by ensuring that macOS only sees symbols available to it.
• Additionally screenshots were being stored in an incorrect home directory.
• Enhancement added that allows specifying what XCUIScreenshotProviding object should be screenshotted. This is useful when taking screenshots for macOS and you'd prefer to screenshot the window and not the screen. This does not break backwards compatibility.

For conversations around Snapshot on macOS, please see:

• Snapshot support for macOS projects #11092
• Snapshot with Catalyst fails at latest_simulator_version_for_device #18663

Description

• Added screenshotProvider: XCUIScreenshotProviding = XCUIScreen.main to open class func snapshot(_ name: String, timeWaitingForIdle timeout: TimeInterval = 20).
• Inside if os(OSX) condition of the above mentioned function, removed call of app.typeKey(XCUIKeyboardKeySecondaryFn, modifierFlags: []) and added screenshot saving functionality.
• Wrapped class func fixLandscapeOrientation(image: UIImage) -> UIImage with #if os(iOS) || os(watchOS) || os(tvOS) as UIImage isn't available on macOS.
• Change macOS cache directory to URL(fileURLWithPath: "/Users/\(NSUserName())")
• Updated screenshot.mac? to check against Apple MacBook instead of MacBook.
• Removed self.top_space_above_device = offset['titleHeight'] # needed for centering the title from put_device_into_background as titleHeight isn't available for Mac.
• Updated references to @config from fetch_config.

Testing Steps

• Followed the fastlane steps on adding Snapshot to an Xcode project (in this case the Xcode project was for macOS).
• Added concurrent_simulators(false) to the snapfile based off the suggestion here: Snapshot with Catalyst fails at latest_simulator_version_for_device #18663 (comment).
• Observed generated html containing screenshots.

[ptrkstr]

This is still in progress. Will get round to it very soon.

[joshdholtz]

@ptrkstr Hey! I love this PR and just wanted to see if there was anything that you needed help with 😊

[ptrkstr]

Hey @joshdholtz thanks for reaching out! I think it should be good to go for review. Maybe one additional change could be that it doesn't require a user to add 'concurrent_simulators(false)' to their snapfile and instead that's ignored if it's snapshotting for mac?

[ptrkstr]

Hey @joshdholtz, bumping this 😌

[MortenGregersen]

Shouldn't we get this merged in, @joshdholtz ?