Move activities into their own leakcanary-identified process

[JakeWharton]

The leak and permission activities have their own task affinity but still reside in the host app's process. This means they're subject to whatever happens in the Application.onCreate unlike the leak analysis service. In our case, we set up a violently punishing strict mode which the leak display activity violates (and thus crashes).

Instead of adding a bunch of try/finally blocks to disable strict mode around the harmless disk reads on the main thread in the leak display activity, it would be better if these activities had their own process which was identified as being leak canary-owned by the LeakCanary.isInWhateverProcess method. It doesn't have to be the same process as the analysis service, just a non-default one that in turn skips the normal application creation process just like the service would.

[JakeWharton]

And I can do this if it seems like an acceptable change.