[llvm] [TableGen] Emit OpName as an enum class instead of a namespace (PR #125313)

[Sergei Barannikov via llvm-commits]

s-barannikov wrote:

> * Add OpName::NUM_OPERAND_NAMES as an alias for OPERAND_LAST (to be deprecated).

I don't think it needs to be deprecated, this is a trivial change.


https://github.com/llvm/llvm-project/pull/125313