Copy sharing/internal, sharing/common and sharing/scheduling to github.

- Move Abseil pin to same as that used in Chromium.
- Disabled layering_check due to build failure in absl.

PiperOrigin-RevId: 596631921

internal/platform/implementation/apple/BUILD

@@ -17,7 +17,7 @@ package(default_visibility = [
     "//connections:__subpackages__",
     "//internal/platform/implementation/apple:__subpackages__",
     "//location/nearby:__subpackages__",
-    "//third_party/nearby/sharing:__subpackages__",
+    "//sharing:__subpackages__",
 ])
 
 objc_library(