[llvm] [llvm-support][llvm-profdata] Use cl::Subcommand to organize show options. And look up in top-level as a fallback if a special subcommand doesn't have an option. (PR #71328)

[Mingming Liu via llvm-commits]

minglotus-6 wrote:

This is ready for review again! 

Some options are sub-command specific and I tried to keep these options closer to where they are used. Common options are moved ahead at the very beginning. 

https://github.com/llvm/llvm-project/pull/71328