Switch to HexEncoding from ByteStringUtils

Migration in preparation for deletion of ByteStringUtils.

Also contains an import ordering change needed for upload.

Bug: 124232146
Test: build only
Change-Id: I0c71751de9a142a81ce43b4eaea497bf291afcbc
(cherry picked from commit 8fdca745d62f2d754d30ebbac95cf1c9f0456287)
1 file changed