[mlgo] bazel rules for mlgo-utils

[mtrofin]

Akin the py_binary rules for lit, these are scoped to binaries, rather than exposing the library - binary split. The latter is available to the package (pip package) users.

Tested:

cd utils/bazel
bazel build @llvm-project//llvm:extract_ir
bazel-bin/external/llvm-project/llvm/extract_ir --help

...and observed expected output (rather than import not found errors)

(Same for the other 2 targets).

[boomanaiden154]

I'm assuming the point of this PR is to just expose the binaries so they can be used with Bazel and there isn't a (current) need to expose any of the libraries as Python libraries?

[mtrofin]

I'm assuming the point of this PR is to just expose the binaries so they can be used with Bazel and there isn't a (current) need to expose any of the libraries as Python libraries?

correct.

[boomanaiden154]

LGTM. If we ever need to support use as a library in the future, it should be easy to refactor. Not sure py_library is a good fit right now just for this use case, not really familiar with the canonical way to do things in bazel however.

[GMNGeoffrey]

I no longer work with LLVM (or on compilers, or at Google, or with Bazel), so am not the right reviewer for this. Added @aeubanks