Flag potential "similar layers"

[aparlato]

https://docs.mapbox.com/help/troubleshooting/mapbox-gl-js-performance/#similar-layers

Performance-wise, the best thing you can do for a stylesheet is to combine layers (reducing the overall number of layers), but there's also a benefit to making similar layers more similar by "grouping" them (making certain properties outlined here identical across layers). "Grouped" layers render faster, close to as if it were a single layer.

Could the performance linter have functionality to identify layers that could potentially be grouped (because they're already very similar across these fields)? We may not want this as a standard output since it would just be to help a human make decisions because it's not clear cut, but I could see a benefit in identifying layers that are nearly the same.