This commit splits the generic part of `LoopInfo` into separate files.
These new `GenericLoopInfo` files are located in `llvm/Support` to be inline
with `GenericDomTree`.
Furthermore, this change ensures that MLIR's Bazel build does not have
to link against `LLVMAnalysis` just to use these template headers.
Depends on D148219
Reviewed By: ftynse
Differential Revision: https://reviews.llvm.org/D148235
f5425c128a