The SBOM implementation got somewhat large. Split the code into
several new QtPublicSbomFooHelpers.cmake files, to make it more
manageable.
No code or behavior was changed.
Pick-to: 6.8
Task-number: QTBUG-122899
Change-Id: Ia0ca1792eec21d12c4bb4cabe63279e1f5c07e3d
Reviewed-by: Alexey Edelev <alexey.edelev@qt.io>
(cherry picked from commit 27d2b54b5d2bc5a69edc2de703b2ca34cb2637dc)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>
