Problem/Motivation
Follow-up to #2611758: Field UI table is broken for nested elements
#description, #field_prefix, #field_suffix, #prefix and #suffix are used by contrib modules to add specials for elements, but they have to call render and merge strings
Proposed resolution
Threat #description, #field_prefix, #field_suffix, #prefix as render array
Remaining tasks
find performant BC to make it 8.x-able
patch, commit
User interface changes
API changes
Data model changes
