[InstrProf] Add vtables with type metadata into symtab (#81051)

The indirect-call-promotion pass will look up the vtable to find out
the virtual function [1],
and add vtable-derived information in icall
candidate [2] for cost-benefit analysis.

[1] https://github.com/llvm/llvm-project/pull/81442/files#diff-a95d1ac8a0da69713fcb3346135d4b219f0a73920318d2549495620ea215191bR395-R416
[2] https://github.com/llvm/llvm-project/pull/81442/files#diff-a95d1ac8a0da69713fcb3346135d4b219f0a73920318d2549495620ea215191bR195-R199