[LV] Support widened induction variables in epilogue vectorization.

[LV] Support widened induction variables in epilogue vectorization.

Code generation now uses the start VPValue of induction recipes.

This makes it possible to adjust the start value of the epilogue
vector loop to use the 'resume' value of the main vector loop.

Fixes #59459.

Reviewed By: Ayal

Differential Revision: https://reviews.llvm.org/D92132