fix: declare PyInfo as provided by test/binary/library

[layus]

Currently, the rules don't advertise the PyInfo provider through the provides argument
to the rule function. This means that aspects that want to consume PyInfo can't use
required_providers to restrict themselves to the Python rules, and instead have to
apply to all rules.

To fix, add PyInfo to the provides arg of the rules.

Fixes #2506

[rickeylev]

This mostly LGTM. The one thing to do is update the changelog.

I renamed this to fix instead of feature. They should have always been declared.

[layus]

@rickeylev Thank you for pushing this over the line. I planned to do it today, and it seems you did all the remaining work 👏 🙇

[rickeylev]

You're welcome!