Add a wavpack default configuration to the badfiles plugin

[Serranya]

Description

Wavpack files can now be verified by the badfiles plugin without addition configuration by the user.

• [x] Documentation. (If you've added a new command-line flag, for example, find the appropriate page under docs/ to describe it.)
• [x] Changelog. (Add an entry to docs/changelog.rst to the bottom of one of the lists near the top of the document.)
• [ ] Tests. (Very much encouraged but not strictly required.)