[llvm] [Bazel] Support opt-driver library, like clang-driver (PR #79205)

[William Moses via llvm-commits]

wsmoses wrote:

@efriedma-quic added a CMake Library for opt. I presume we should add one for clang as well, but that should probably be a separate PR.

https://github.com/llvm/llvm-project/pull/79205