[Sema] Add missing entries to the arrays in GetImplicitConversionName and GetConversionRank.

It appears that ICK_Zero_Queue_Conversion was inserted into the ICK
enum without updating this table. Easy to do since the table size
was set to ICK_Num_Conversion_Kinds.

I've used ICR_Exact_Match to match what was previously done for
ICK_Zero_Event_Conversion that last time someone noticed this had happened.

To prevent this from happening again, I've removed the explicit size
and used a static_assert to check the size against ICK_Num_Conversion_Kinds.

Differential Revision: https://reviews.llvm.org/D144990