Implement importBuffer for BufferHubService

Allow user importBuffer by a previously generated handle from
IBufferClient::duplicate.

Passing a nullptr or invalid token to the service will get a nullptr
IBufferClient and BufferHubStatus::INVALID_TOKEN.

Test: BufferHubBuffer_test (passed)
Change-Id: I0aa969a9706e42039ac851acb991b3aceb924c27
Fix: 118614157
diff --git a/libs/ui/tests/Android.bp b/libs/ui/tests/Android.bp
index b7ad4e5..00f30a6 100644
--- a/libs/ui/tests/Android.bp
+++ b/libs/ui/tests/Android.bp
@@ -53,6 +53,7 @@
     ],
     shared_libs: [
         "android.frameworks.bufferhub@1.0",
+        "libcutils",
         "libhidlbase",
         "libhwbinder",
         "libpdx_default_transport",