Roll Flutter Engine from ed498f111d53 to 6a7f963dc751 (4 revisions) (#142176)

https://github.com/flutter/engine/compare/ed498f111d53...6a7f963dc751

2024-01-24 skia-flutter-autoroll@skia.org Roll Fuchsia Linux SDK from kYC2-fFgjbb36mukB... to Igt2rE-R6rgfmTRaF... (flutter/engine#50015)
2024-01-24 skia-flutter-autoroll@skia.org Roll Skia from 9ea7cb490804 to 643160445720 (6 revisions) (flutter/engine#50014)
2024-01-24 robert.ancell@canonical.com Add custom FlValue types and support their en/decoding via FlStandardMessageCodec (flutter/engine#49162)
2024-01-24 matanlurey@users.noreply.github.com Do not double-increment `nextId` when using `createSurfaceProducer` with `SurfaceTexture`s (flutter/engine#50011)

Also rolling transitive DEPS:
  fuchsia/sdk/core/linux-amd64 from kYC2-fFgjbb3 to Igt2rE-R6rgf

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 jacksongardner@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://issues.skia.org/issues/new?component=1389291&template=1850622

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

bin/internal/engine.version

-ed498f111d530a228ae47c979251a3cd3b738d96
+6a7f963dc751d818cd66a18341b9b87df16c4327

bin/internal/fuchsia-linux.version

-kYC2-fFgjbb36mukBKjz0ZdLNghl9uA5VnmVZMd-pQQC
+Igt2rE-R6rgfmTRaFN4o9HSidg6Fdjy806KmcIvRniQC