Merge branch 'stable-3.0'
* stable-3.0:
Upgrade bazlets to latest stable-3.0 to build with 3.0.2 API
Upgrade bazlets to latest stable-2.16 to build with 2.16.11.1 API
Fixes to build, run, and test on Gerrit 3.0
Support outputting elapsed evaluation time on tasks
Rename some local task variable to be more consistent
Support optional preload-task
Add optional chainable subtask support
Allow tasks attributes to be preloaded from other tasks
Detect and handle non-existing tasks more explicitly.
Use NOT notation in task tests instead of "-"
Clarify applicable queries in task tests
Support exporting properties to task json
task: add support to set custom properties
Add duplicate subtask handling and tests
Move invalid and NA task tests back to bottom.
Add basic task loop detection test
task: create property expansion framework
Tasks: add support for a ${_name} property
Remove buggy undocumented support to redefine task name
Upgrade bazlets to latest stable-3.0
Upgrade bazlets to latest stable-2.16 to build with 2.16.10 API
Upgrade bazlets to latest stable-3.0 to build with 3.0.1 API
Upgrade bazlets to latest stable-2.16
Upgrade bazlets to latest stable-2.16 to build with 2.16.9 API
Change-Id: I58b2615f30d0c588609fad8fe00a752e9c808f9e
