Link tahoe-great-black-swamp into the Android build

Like #13 (closed) but for https://whetstone.private.storage/PrivateStorage/tahoe-great-black-swamp

This one doesn't block #11 (closed) but it will block a later issue where we actually do network operations.

This might involve changes to either or both of PrivateStorageMobile and tahoe-great-black-swamp.