Automatic merge from submit-queue (batch tested with PRs 41378, 41413, 40743, 41155, 41385)
'core' package to prevent dependency creep and isolate core functiona…
**What this PR does / why we need it**:
Solves these two problems:
- Top level Scheduler root directory has several files in it that are needed really by the factory and algorithm implementations. Thus they should be subpackages of scheduler.
- In addition scheduler.go and generic_scheduler.go don't naturally differentiate themselves when they are in the same package. scheduler.go is eseentially the daemon entry point and so it should be isolated from the core
*No release note needed*
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