add variant of Fubini lemmas and rename to clarify

[affeldt-aist]

Motivation for this change

When working on the sampling branch, we realized that we need variants of existing Fubini lemmas but adding these variants was no compatible with the current naming scheme. This PR introduces the variants and change the naming scheme to something easier to comprehend.

Checklist

• [x] added corresponding entries in CHANGELOG_UNRELEASED.md

~~- [ ] added corresponding documentation in the headers~~

Reference: How to document

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