[llvm] [bazel] Add rules for clang-fuzzer protobuf-related libraries (PR #123126)

[NAKAMURA Takumi via llvm-commits]

chapuni wrote:

> Do you mean only the proto-related stuff, or everything clang-fuzzer? If it's the former, we don't need to exclude `clang-fuzzer-initialize` because it doesn't depend on protobufs. And if it's the latter, we'd also need to exclude/move some other recently-added targets like `clang-fuzzer-dictionary` and `handle-cxx`.

Thanks for your considerations.
Practically the former but it'd be better able to exclude stuff controlled by `CLANG_ENABLE_PROTO_FUZZER`.

 I am using `@llvm-project` for bootstrapping clang toolchain. `clang-fuzzer` is not required for now.
My builder has the stage for comparison of each relocatable-object.o file CMake tree and Bazel tree but I want to build much target as possible. (Note, almost all files can be made identical with my toolchain and toolchain's clang can be made identical to the final artifact clang)

I don't use the in-tree `WORKSPACE`. Ultimately I will have to configure protobuf but for now I would like to keep minimal configuration.

https://github.com/llvm/llvm-project/pull/123126