[llvm] [mlgo-utils] Create top level entrypoint scripts for mlgo-utils (PR #146981)

[Aiden Grossman via llvm-commits]

boomanaiden154 wrote:

> n alternative is to have a symlink of the script to the mlgo-utils directory

I think a symlink would be fine for now.

> It's not the cwd of the interpreter. It's just placed incorrectly if invoked directly from python3. The file imports from mlgo and the script lives inside it when it should live beside it. 

Buck doesn't do anything to `$PYTHONPATH`? The following works just fine for invoking one of the scripts:

```
cd llvm/utils/mlgo-utils
PYTHONPATH=$PYTHONPATH:. python3 ./mlgo/corpus/extract_ir.py
```

https://github.com/llvm/llvm-project/pull/146981