[llvm] Migrate llvm-profdata to Opt flag parsing (PR #177868)

[Petr Hosek via llvm-commits]

petrhosek wrote:

cc @Prabhuk since this the first real use of `SubCommand` support in `OptTable` which he implemented in https://github.com/llvm/llvm-project/pull/155026.

https://github.com/llvm/llvm-project/pull/177868