suite_sets: add more complex validation checks

Add checks ensuring  all csuite ids are unique, all sub-csuites exist,
and no cycles exist.

BUG=b:323238878
TEST=ran config presubmits

Change-Id: Ic2207990c5d27139fe84e43feef252e6c3a05e6d
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/dev-util/+/5315436
Commit-Queue: Jack Gelinas <jackgelinas@google.com>
Reviewed-by: Brett Brotherton <bbrotherton@google.com>
Tested-by: Jack Gelinas <jackgelinas@google.com>
Reviewed-by: Derek Beckett <dbeckett@chromium.org>
2 files changed