Roll Flutter Engine from a687d62ff631 to 46d5ce4784b8 (1 revision) (#125874)

https://github.com/flutter/engine/compare/a687d62ff631...46d5ce4784b8

2023-05-02 zhongwuzw@qq.com [macOS] Add lookupKeyForAsset to FlutterPluginRegistrar (flutter/engine#37421)

If this roll has caused a breakage, revert this CL and stop the roller
using the controls here:
https://autoroll.skia.org/r/flutter-engine-flutter-autoroll
Please CC jsimmons@google.com,rmistry@google.com,zra@google.com on the revert to ensure that a human
is aware of the problem.

To file a bug in Flutter: https://github.com/flutter/flutter/issues/new/choose

To report a problem with the AutoRoller itself, please file a bug:
https://bugs.chromium.org/p/skia/issues/entry?template=Autoroller+Bug

Documentation for the AutoRoller is here:
https://skia.googlesource.com/buildbot/+doc/main/autoroll/README.md

bin/internal/engine.version

-a687d62ff6314a3b5675d298b76c1576927cd2a2
+46d5ce4784b881f24c7b1e54eabbb0b0008163d6