Objective-C ffigen should test against all Apple APIs

[brianquinlan]

There should be an integration test that runs ffigen against all of Apple's headers and verifies that the resulting generated file passes analysis.

Bonus points for spot-checking that some complex classes, protocols, etc. are usable.

[liamappelbe]

There are 4383 headers across 255 frameworks in my Apple SDKs directory (matching /Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/System/Library/Frameworks/*.framework/Headers/**.h).
When I try to generate bindings for all of them, it runs for 35min then crashes with no useful info (not sure if it's a legit bug, or if my laptop just ran out of memory or something).

So instead of pulling in all these headers as a glob, I'm going to add one framework at a time until something breaks.

[liamappelbe]

There's one more bug that needs to be fixed before this can land: #1220

[liamappelbe]

Tried running this test on the github CI bots in #1554. Unfortunately they don't really have enough memory to run this test without thrashing (see dart-lang/sdk#56247). So what should be a 30sec analysis times out after 30min.

I added a randomized filter that removes 90% of the bindings, and that allows the test to complete.