feat(make): implement iOS build (#316)

Part of https://github.com/ooni/probe/issues/1440.

Basically, let us continue to update our build infrastructure so that we can release v3.10.0-beta.

Now, it's the turn of iOS.

.github/workflows/ios.yml

@@ -6,10 +6,7 @@ on:
       - 'release/**'
 jobs:
   test:
-    runs-on: macos-latest
+    runs-on: macos-10.15
     steps:
-      - uses: actions/setup-go@v1
-        with:
-          go-version: "1.16"
       - uses: actions/checkout@v2
-      - run: ./build-ios.bash
+      - run: ./make --disable-embedding-psiphon-config -t ios