Include microdroid files to virt apex

All files to run microdroid is now included to the com.android.virt
APEX:

- super image
- boot images
- vbmeta images
- bootloader
- uboot_env image
- cdisk json config

Also the documentation README.md and microdroid host tests are updated
too.

Bug: 184803590
Test: follow instructions on README.md
Test: atest MicrodroidHostTestCases
Change-Id: I71f0e32ca774b351d9f49af2754f0a1c786c2400
5 files changed
tree: 9a0f88821c4d1bd0af803da033e11f23ffce796b
  1. apex/
  2. authfs/
  3. docs/
  4. microdroid/
  5. tests/
  6. virtmanager/
  7. vm/
  8. .clang-format
  9. PREUPLOAD.cfg