Take screenshot when drive fails

[jmagman]

Add --screenshot option to flutter drive to take a screenshot when the tests fail. This should make it easier to debug timeout failures like #78805. Since it doesn't rely on VM's screenshot this should also help us detect that the app launched but is just sitting on a white screen because the engine failed to initialize.

Adopt in devicelab tests to point to the directory that gets uploaded via LUCI recipe.

I purposely regressed #75665 locally, and lo:

[ios_platform_view_tests] [STDOUT] stdout: [   +7 ms] 01:01 +0 -2: Some tests failed.
[ios_platform_view_tests] [STDOUT] stderr: [   +1 ms] Unhandled exception:
[ios_platform_view_tests] [STDOUT] stderr: [        ] Dummy exception to set exit code.
[ios_platform_view_tests] [STDOUT] stdout: [  +59 ms] executing: /Users/magder/Projects/flutter/bin/cache/artifacts/libimobiledevice/idevicescreenshot /var/folders/bx/pyplw7v92lj58gm3_lztz5sc00mfq2/T/flutter_test_logs.qTqzs5/drive_01.png --udid d83d5bc53967baa0ee18626ba87b6254b2ab5418
[ios_platform_view_tests] [STDOUT] stdout: [ +601 ms] Screenshot saved to /var/folders/bx/pyplw7v92lj58gm3_lztz5sc00mfq2/T/flutter_test_logs.qTqzs5/drive_01.png
[ios_platform_view_tests] [STDOUT] stdout: [        ] Screenshot written to /var/folders/bx/pyplw7v92lj58gm3_lztz5sc00mfq2/T/flutter_test_logs.qTqzs5/drive_01.png

I wouldn't have had to SSH into the host to figure out the device was sideways.

[jmagman]

I tried for awhile to get DriveCommand working with the CommandRunner to actually run the test, but I eventually gave up after I couldn't pass in --no-pub

flutter/packages/flutter_tools/lib/src/commands/drive.dart

Lines 142 to 145 in ce318b7

	// `pub` must always be run due to the test script running from source,
	// even if an application binary is used.
	@override
	bool get shouldRunPub => true;

flutter/packages/flutter_tools/test/src/throwing_pub.dart

Line 37 in 74bd7b6

throw UnsupportedError('Attempted to invoke pub during test.');

[jonahwilliams]

hmm, I think this is wrong. We should always run pub by default, unless we're asked not to.

[jmagman]

Past Jonah says #70136

[jmagman]

Let's ignore the Cirrus failures for now as long as the LUCI equivalents pass #78678.

[jonahwilliams]

LGTM

I can take a look at the pub issue tomorrow

[jmagman]

(yeessssss.... #66153 (comment))

[chunhtai]

I ran into issue where local environment does not have FLUTTER_LOGS_DIR

[jmagman]

That's a regression from #84008. Fix out at #84820