[base] Move some files from include/private to include/private/base

These ones were arbitrarily chosen among files that did not have
any dependencies on include/core:
    include/private/SingleOwner.h
    include/private/SkDeque.h
    include/private/SkMalloc.h
    include/private/SkMutex.h
    include/private/SkOnce.h
    include/private/SkSemaphore.h
    include/private/SkStringView.h
    include/private/SkTFitsIn.h
    include/private/SkThreadAnnotations.h
    include/private/SkThreadID.h
    include/private/SkTo.h

Change-Id: I32b945b459922e39e3e40c9f4af134b269d4958a
Bug: skia:13983
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/626078
Commit-Queue: Kevin Lubick <kjlubick@google.com>
Reviewed-by: Herb Derby <herb@google.com>
Owners-Override: Kevin Lubick <kjlubick@google.com>
422 files changed