This patch increases the performance when remapping data.
D13615: Performance: Remap multiple items in UI introduced a mechanism to remap multiple items in a single go.
This patch uses the same mechanism when remapping data inside ID datablocks.
Benchmark results when loading the village scene of sprite fright on AMD Ryzen 7 3800X 8-Core Processor
Before this patch 115 seconds
When patch applied less than 43 seconds
There is still some room for improvement by porting relink code.

