CtsMedia: Update README.md

Updated README.md as per CTS reorganization

Also added copy_media.sh for each of the subdirs and added
a copy_all_media.sh that invovkes all of these

Bug: 223679154
Test: Review

Change-Id: I05f8964ff4df2c32cecdff224c4a66f011a7a2a6
12 files changed