Roll Flutter Engine from 683bca53d4d7 to 45bc4307cda3 (2 revisions) (#134789)

https://github.com/flutter/engine/compare/683bca53d4d7...45bc4307cda3

2023-09-14 goderbauer@google.com Enable private field promotion (flutter/engine#45722)
2023-09-14 bdero@google.com [Impeller] Add Entity::RenderingMode enum. (flutter/engine#45845)

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 bdero@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

-683bca53d4d72e5bb891006dac0e75b667a792d8
+45bc4307cda3f7af61915d5d7875d9ccb6bc637d