[DisplayList] Optimize draws of simple shapes expressed as paths

[flar]

Fixes flutter/flutter#151849

Originally part of #53622 which had to be reverted due to incompatible scuba changes. This part was split out as the likely culprit in the scuba failures and eventually an issue was found with the way the original code was written which failed to properly handle unclosed rectangles. This version fixes that bug.

[jonahwilliams]

Can we also start removing some of the optimization logic from the dispatcher: https://github.com/flutter/engine/blob/main/impeller/display_list/dl_dispatcher.cc#L993-L1024

I see there are other places that flow through SimplifyOrDrawPath so we probably can't remove tht yet, but it will be simpler long term if the dispatcher is dumber.

[chinmaygarde]

Based on the conversation I had with Jim the other day, I think we are going to abandon this as tiny changes to rendering results were observed with the Skia backend. Am I thinking of the right bug?

[flar]

Correct. We'll revisit this later when we have only 1 backend.