refactor: resolve reported VPTO codecheck findings

[HecreReed]

Summary\n\n- simplify materializeMemRefView by moving tile-specific type construction to its caller\n- add braces to the control flow reported in VPTOCANN900LLVMEmitter.cpp\n- replace the reported getS accesses with generic result/operand accessors\n- remove the file-wide -Woverloaded-virtual suppression\n- reduce Mad and VCVT callee-selection complexity with contract tables\n- table-drive load distribution immediate parsing and share checked shifted-field packing\n- hoist VCVT contracts out of the lookup function so the function only performs lookup\n\nThis Draft PR covers both files from the supplied codecheck report and remains intentionally scoped to those files.\n\n## Validation\n\n- git diff --check\n- VPTOBufferMaterialization.cpp.o builds with project C++17 and -Werror\n- lizard: Mad dispatch and VCVT lookup are below the reported complexity threshold; load distribution parsing is table-driven\n- emitter compile reaches only unchanged LLVM-environment incompatibilities: selected LLVM lacks CANN900 low-precision LLVM types and llvm::CallingConv::SimtEntry\n