Now "report" step combines result in a uniform way and processes unit test
results XML output. It works for sub-builds only started from the 'premerge'
pipeline, i.e. non-recursive. One downside is that now one has to wait until
all jobs have finished.
- Add instructions to setup python environment
- added option to do full report cycle but not call Phabricator
- use "annotations" to show build status. That lifts the need to filter ninja
and other output (thus `ph_no_filter_output` param removed) and output
everything. That is nice as script failures no longer lead to loss of logs.
- improved annotate() usability
- misc fixes
- configured sccache on buildkite windows machines
- final result is sent to phabricator from "summary.py" that waits for both builds to complete
- extracted "add_url_artifact" to a runnable script
- reorganized code and fixed some of TODOs
