Expose Python -O/-OO options optimization settings during build

One way to remove sensitive or proprietary information from Python source code is to use `-OO` when compiling `.pyc` files. Since docstrings normally don't affect runtime execution, having this option exposed when building with PyOxidizer would allow a user to strip these strings out of their delivered binary.

This also helps reduce the final size of the binary (#220).

The removing of sensitive information portion of this features relate to #265.

The equivalent CPython command would look like:

```bash
$ python3 -OO -m compileall -b main.py

# Creates main.pyc file without docstrings or assert statements.
```

Start by tracing PyOxidizer's build path for Python bytecode and how it could expose compiler optimization settings; the issue names no file or test. Compare behavior with the shown `python3 -OO -m compileall -b main.py` command. Done means builds can select the documented optimization behavior, including removal of docstrings and assert statements.

Written by the indexing model from the issue text.