[PLAT-8506] Local watchOS E2E testing

[nickdowell]

Goal

Make it possible to run E2E scenarios on Apple Watch.

Scope

Allows running the barebone_tests on watchOS.

Design

Launches the fixture using Xcode 13's xcdebug command-line tool.

The --environment option does not seem to work, so maze runner's host name needs to be compiled into the fixture. The Makefile takes care of this by inserting the computer's IP address.

Changeset

Adds a watchOS fixture - watchOSTestApp in features/fixtures/watchos

Amends features/barebone_tests.feature to be compatible with watchOS.

BareboneTestUnhandledErrorScenario has been changed to an uncaught NSException because it's not possible to detect Swift fatal errors.

Testing

Run the tests with make e2e_watchos

An iPhone with paired Apple Watch must be connected and available in Xcode's devices window.

See TESTING.md

[github-actions]

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[twometresteve]

Test/CI approach looks good to me, but could we have something in TESTING.md detailing how to run the tests on watchOS (and to some extent advertise that it's possible)?