Write session state in APEX storage.

When a session is submitted for staging, write this state in /data/apex.
In a future CL, instead of scanning /data/staging, we will scan APEX
private storage to look for packages to be activated.

Bug: 118865310
Test: builds, apexservice_test still passes
Change-Id: I6ea1b177c50648e1c95fa695cedaafed8b8530bd
6 files changed
tree: 4f895650f589cc279b08d848a61449885a950a89
  1. apexd/
  2. apexer/
  3. proto/
  4. tests/
  5. OWNERS
  6. PREUPLOAD.cfg