Add replaceRangeAssumeCapacity method to ArrayList

[g-cassie]

Adds replaceRangeAssumeCapacity method. This feels like it's missing based on the other methods that are available in ArrayList.

Also refactor orderedRemove to just call out to replaceRange. Happy to revert this part if it's not the right vibe.

Are there any patterns for parametrizing tests in zig? Seems like it could help a lot here testing the 4 different types of ArrayLists.