[Plat-11665] New mazerunner api

[kstenerud]

Goal

Update this repo to use the new idempotent mazerunner API so that we can reduce the number of flakes.

Design

This follows the same approach as used in bugsnag-cocoa-performance, with the added twist that we store the most recent maze runner command UUID in NSUserDefaults so that the data survives app restarts (because we are deliberately crashing the app).

Changes

This PR unfortunately has a huge number of changed files, but most of them are very small, repetitive changes.

• Every scenario has been modified to override configure instead of configuring in the startBugsnag method. This accounts for most of the changed files. Some scenarios have been updated to become more robust to the new timing.
• The various .feature files needed to be updated for the different timing we now have, and to remove some old workarounds that are no longer relevant.
• macOSTestApp and iosTestApp saw the most big changes in order to make them use the Fixture class rather than driving things itself.
• eventMode has been removed, and instead every command takes a list of arguments. For example in AppHangScenario.swift, TimeInterval(eventMode!)! is now TimeInterval(args[0])!.
• performBlockAndWaitForEventDelivery has been replaced with waitForEventDelivery:andThen because the old approach blocked the main thread, which can cause the app to hang. Similarly for performBlockAndWaitForSessionDelivery
• All scenario and fixture configuration has been moved into FixtureConfig.
• CommandReaderThread.swift, Fixture.swift, and MazeRunnerCommand.swift are copied from BugsnagPerformance with a few minor changes.

Testing

There is no new functionality - We're just changing the testing rig.

[github-actions]

Bugsnag.framework binary size did not change - 713,264 bytes

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[twometresteve]

Great change!