[DWARFVerifier] Allow overlapping ranges for ICF-merged functions (#117952) This patch modifies the DWARF verifier to handle a valid case where two or more functions have identical address ranges due to being merged by ICF (Identical Code Folding). Previously, the verifier would incorrectly report these as errors, but functions merged via ICF (such as when using LLD's --keep-icf-stabs option) can legitimately share the same address range. A new test case has been added to verify this behavior using YAML-based DWARF data that simulates two DW_TAG_subprogram entries with identical address ranges. The test ensures that the verifier correctly identifies this as a valid case and doesn't emit any errors, while still maintaining the existing verification for truly invalid overlapping ranges in other scenarios. Before this change, the newly added test case would have failed, with `llvm-dwarfdump` marking the overlapping address ranges in the DWARF as an error. We also modify the existing tests `llvm-dwarfutil/ELF/X86/verify.test` and `llvm/test/tools/llvm-dwarfdump/X86/verify_parent_zero_length.yaml` which rely on the existence of the error that we're trying to suppress. We slightly change one offset so that the ranges don't perfectly overlap and an error is still generated.
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