Reland "[NFC] SimplifyCFGOptions: drop multi-parameter ctor, use default member-init"

This reverts commit 5831e861,
which reverted commit 90c1b044
in preparation for reverting
commit b2018198 in
commit 1067d3e1 due to the introducton
of a dependency cycle.

Now that the other revert is reverted with a fix, this can be relanded.