Merge topic 'ctest-loop-idle'

086a41c0f3 cmCTestMultiProcessHandler: Simplify test startup batching
e528cd795f cmCTestMultiProcessHandler: Start new tests asynchronously
9d8415c17b cmCTestMultiProcessHandler: Clarify test-load retry timer infrastructure
61e98ca33b cmCTestMultiProcessHandler: Factor out loop startup and teardown
5ff0b4ed57 cmCTestMultiProcessHandler: Consolidate test readiness checks
ad3df3ce4d cmCTestMultiProcessHandler: Exclude dependent tests earlier
3c4767f467 cmCTestTestHandler: Clarify name of member storing RESOURCE_LOCK property

Acked-by: Kitware Robot <kwrobot@kitware.com>
Acked-by: buildbot <buildbot@kitware.com>
Merge-request: !8995