Revert "Revert "Inital support for staged sessions.""

This reverts commit 4984421778871234896b0a1f6f90f3051ea1b0d4.

Reason for revert: Will re-submit together with the appropriate SELinux changes, which were in a separate unsubmitted CL.

Bug: 118865310
Test: atest apex_e2e_tests with a modified version of tradefed which uses
the --staged PackageManager option (being developed as an internal change)
Change-Id: I202dff9cf15150cfaa316c8221e89999cbaf9f77
3 files changed
tree: b9488cd51c407b246e54bf4eb82441cf57c5fad5
  1. apexd/
  2. apexer/
  3. proto/
  4. tests/
  5. OWNERS
  6. PREUPLOAD.cfg