[bazel] Add support for LLVM_TOOL_LLVM_DRIVER_BUILD (#86879)

This adds the bazel equivalent of the `llvm` binary produced by
`LLVM_TOOL_LLVM_DRIVER_BUILD` in cmake. For the initial commit, this
only includes `llvm-ar`, `llvm-nm`, and `llvm-size`. The rest are
trivial to add in a followup commit, following the same pattern as here.

By default it will include everything that supports the llvm-driver
model, but it can be reduced to only build a subset, e.g. this will
build only nm and size:

```
$ bazel build \
    --@llvm-project//llvm:driver-tools=llvm-nm,llvm-size \
    @llvm-project//llvm:llvm
```