Mac OS: reorganize FTE packaging

To finish #13252 (moved) and #6540 (moved), we need to change the way the FTE client is packaged in Tor Browser. Specifically, to meet Apple's Gatekeeper code signing requirements we should put all of the files that do not contain compiled object code (e.g., the Python scripts) under:

TorBrowser.app/Contents/Resources/TorBrowser/Tor/PluggableTransports/fte/

and we should put all of the binaries (compiled executables and shared libraries) under: TorBrowser.app/Contents/MacOS/Tor/PluggableTransports/fte/

Kevin -- it would be very helpful to have your assistance with this task. Kathy and I have limited Python knowledge and very little FTE knowledge.