zipfuse now runs in microdroid as a service. The source zip file path
and the mount point are fixed to /dev/block/by-name/microdroid-apk and
/mnt/apk, respectively.
To support that, microdroid_payload.json is amended to add
MicrodroidTestAppk.apk to the payload.img file. This eventually should
be done dynamically by the virt manager.
Bug: 186377508
Test: atest MicrodroidHostTestCases
Change-Id: I7a031ad442995dbd3cdc00a51a0e939c1589a7b2