[llvm] [llvm][Support] Add YAMLSchemeGen for producing YAML Schemes from YAMLTraits (PR #133284)

[via llvm-commits]

tgs-sc wrote:

@jh7370, I apologize in advance, but I saw that you recently looked at a patch to add new functionality (new virtual error method) to this part of llvm for working with the yaml format. Could you please look at this patch, because it also adds some new functionality without breaking backward compatibility.

https://github.com/llvm/llvm-project/pull/133284