conditional_fields 8.x-1.0-alpha8

High-level changes since 8.x-1.0-alpha7:

• Fixed a massive performance degradation. If your form submissions are ridiculously slow, this should fix that.
• All tests are now passing again.

Detailed changes since 8.x-1.0-alpha7:

• #3086250 by sboden, tbenice, mindaugasd, solide-echt, Kris77, SocialNicheGuru: Perform form validation once per form. (#)
• #3086250 by colan: Reversed the order of functions for readability, and fixed minor coding standards issues. (#)
• #3134183 by nuez: Fixed broken tests. (#)