Baseline: 0803ad3770155be411a703950502dc71743017bd

Important changes:

  - Added `--experimental_collect_skyframe_counts_in_profiler` to
    collect Skyframe node counts in the JSON profile over time.
    Currently, the following SkyFunctions are measured: `BZL_LOAD`,
    `GLOB`, `GLOBS`, `PACKAGE`, `CONFIGURED_TARGET`, `ASPECT`,
    `ACTION_EXECUTION`.

This release contains contributions from many people at Google, as well as Fabian Meumertzheim, Jamison Lahman, Jordan Mele, Son Luong Ngoc.