updates tailscale/tailscale#15802
This adds the required targets to build for the iOS
simulator. We support both ios, ios-sim, and ios-fat
framework targets.
The sample app is updated to link in the ios-fat version
so it can be run on any target device or sim.
updates tailscale/tailscale#13937
Adds a Makefile for building various targets. Adds support for building
iOS compatible libtailscale_ios.a. Removes SOCKS5 support for iOS where
it looks like the CFNetwork support is lacking.
Fixes a few unexported symbols in TailscaleKit.
Added macOS sample app.