https://discourse.llvm.org/t/rfc-profile-guided-static-data-partitioning/83744
proposes to partition static data sections.

This patch introduces a codegen pass. This patch produces jump table
hotness in the in-memory states (machine jump table info and entries).
Target-lowering and asm-printer consume the states and produce `.hot`
section suffix. The follow up PR
https://github.com/llvm/llvm-project/pull/122215 implements such
changes.

---------

Co-authored-by: Ellis Hoag <ellis.sparky.hoag@gmail.com>

This registers the pass with PassRegistry so we can use -start-before
and other options for machine-function-splitter.

The existing analysis was already a pimpl wrapper.

I have extracted legacy pass logic to a LDVImpl wrapper named
`LiveDebugVariables` which is the analysis::Result now. This controls
whether to activate the LDV (depending on `-live-debug-variables` and
DIsubprogram) itself.

The legacy and new analysis only construct the LiveDebugVariables.

VirtRegRewriter will test this.

With this, all machine SSA optimization passes are available in the new codegen pipeline.