Support building wheel in spacy package

[ines]

Description

Allow spacy package to build binary wheels by introducing a unified --build option that defaults to sdist (but can also be set to wheel, sdist,wheel or none). Building the wheel will then run setup.py bdist_wheel under the hood.

Types of change

enhancement

Checklist

• I have submitted the spaCy Contributor Agreement.
• I ran the tests, and all new and existing tests passed.
• My changes don't require a change to the documentation, or if they do, I've added all required information.

[honnibal]

Looks good! Go ahead and merge when ready :)