refactor: resolve reported VPTO codecheck findings - #1355

Scope

This PR only addresses the supplied codecheck findings in:

• lib/PTO/Transforms/VPTOBufferMaterialization.cpp
• lib/PTO/Transforms/VPTOCANN900LLVMEmitter.cpp and its new private implementation units

Changes

• Simplify memref-view materialization while preserving tile and layout semantics.
• Add braces to the reported control-flow statements and replace the flagged getS accessors.
• Remove the file-wide warning suppression and reuse checked shifted-field packing helpers.
• Reduce the reported Mad, VCVT, load-distribution, and lowering-path complexity with focused helpers and table-driven dispatch.
• Split the CANN 9.0 emitter into cohesive translation units; every resulting .cpp remains below 2,000 NBNC lines.
• Preserve all 253 lowering-pattern registrations across the split.
• Restore FP8/HIF8 MAD dispatch coverage exposed by simulator CI.

Validation

• git diff --check
• Lizard: 559 functions checked, no function above 50 lines or cyclomatic complexity 20.
• Remote LLVM 19 build: ninja -C build -j64 PTOASPythonPackage
• Focused remote regression: mad_hif8 VPTO emission passed.
• Remote regression suite: 1,844 passed, 1 unsupported, 0 failed (ninja -C build -j64 check-pto).