Updates the platform shims in dev/manual_tests so that Windows and Linux can be built. I had to update the Windows shims, because I was unable to build a Windows app there.
Also updates the analyze.dart script to report all license issues simultaneously instead of just dying after the first failure.
The only substantive code changes are in dev/bots/analyze.dart and dev/bots/test/analyze_test.dart
I updated the build files for manual_tests, as well as adding in a macos and web directory to allow the manual tests to be run on the web or on desktop.
The main change here are the parts that I added to the files in manual_tests/lib/... (the addition of kIsWeb to "if (!kIsWeb && Platform.isMacOS) {") The rest is just an update of the auto-generated code from flutter create.
