adb: implement LZ4 compression.

Add support for LZ4 compression, which compresses and decompresses far
more quickly than brotli, at the cost of worse compression ratio.

`adb sync -d system` speeds (in MB/s) on aosp_blueline-eng:

           none    brotli    lz4
USB 3.0     120       110    190
USB 2.0      38        75     63

Bug: https://issuetracker.google.com/150827486
Test: python3 -m unittest test_device.FileOperationsTest{Uncompressed,Brotli,LZ4}
Change-Id: Ibef6ac15a76b4e5dcd02d7fb9433cbb1c02b8382