Face mesh IOS static framework example

[maletsden]

Change List:

• Refactored MediaPipe repo to have the possibility to use face mesh as a static library
• Added example for creating IOS static framework

Build:

bazel build --config=ios_disable_gpu_arm64 mediapipe/examples/ios/face_mesh_static:FaceMeshCpu

Output:

• FaceMeshCpu.framework - IOS static framework that still requires Bazel external headers (such as absl, ...), which for now need to be copied by hand