Rename android.media.MediaTranscodeManager -> MediaTranscodingManager

renamed to avoid conflict with existing copy in the R framework.jar.
The framework.jar copy was removed during S development

Bug: 195608856
Test: build
Test: cts-tradefed run cts -m CtsMediaTranscodingTestCases
Change-Id: I6e9616b889f898fa9fa3e33a8bf379a77ca6fb72
(cherry picked from commit 0c4e053b454656496f02c51579b7be65a96d4f4e)