Raise targetSdkVersion to 29, package Tor binaries as libraries
This branch raises the target API level to 29 and changes the way we package the Tor and obfs4 binaries so the installer unpacks them to the library dir, as executing binaries from the app's data dir is not allowed when targetting API >= 29.
90% of the code in this branch is a workaround for a bug in the installer that sometimes prevented libraries from being extracted to the library dir on app updates.
On API < 29 we can work around this by extracting the binaries to the data dir ourselves. On API >= 29 there's no workaround, so hopefully the installer bug has been fixed...
Tested on API 16, 29 and 30 emulators and Pixel 2 (API 30).