[4.x] Fixes for asset/term reference updater strictness

[jesseleite]

This PR takes over from where #7555 and #9790 left off, but addresses more edge cases.

• Asset reference updater
  • Ensure we handle string/array values regardless of max_files configuration
  • Ensure we handle string/array values regardless of save_html configuration
  • Add test coverage for the above
• Term reference updater
  • Ensure we handle string/array values regardless of max_items configuration
  • Ensure we handle string/array values for scoped terms regardless of max_items configuration
  • Add test coverage for the above

Closes and fixes #7555
Closes #9790
Fixes #9701
Fixes #7547
References #7555
References #8114