[llvm] [SelectionDAG] Add support to filter SelectionDAG dumps during ISel by function names (PR #72696)

[Min-Yih Hsu via llvm-commits]

mshockwave wrote:

I've made some major revision to this patch:
  1. Re-use `-filter-print-funcs=<function names>`.
  2. Introducing a new debug type, "isel-dump", for printing SelectionDAG after each ISel phase. This debug type can be filtered by `-filter-print-funcs`.  Note that it is also compatible with the original "isel" type. Namely, `-debug-only=isel` will still print the full, unfiltered debug output regardless the value of `-filter-print-funcs`.

https://github.com/llvm/llvm-project/pull/72696