Most notable public API change is that '../' is no longer allowed in
lucicfg.emit(dest=...).

R=tandrii@chromium.org

Change-Id: Iff162c6e1cbd0c7fcbbafc8b2f56eb827660aa93
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/1880301
Auto-Submit: Vadim Shtayura <vadimsh@chromium.org>
Reviewed-by: Andrii Shyshkalov <tandrii@google.com>
Commit-Queue: Andrii Shyshkalov <tandrii@google.com>