Adds a bit more clarifying documentation to the implementation of the
outputFollowsExit case, and adds tests that verify the behaviour of
stderr, stdout of processes launched via FakeProcessManager.

Specifically:
* Verifies that stderr, stdout are not emitted immediately after process
  exit if outputFollowsExit is true. They must be emitted at least one
  turn through the event loop later.
* Verifies that ProcessResult.stderr, stdout have the type documented
  according to the encoding passted to Process.run/runSync:
  * List<int> if null is passed as the encoding.
  * String (in the default system encoding) if no encoding is specified.
  * String (in the specified encoding) if an encoding is specified.

This is additional testing relating to refactoring landed in:
https://github.com/flutter/flutter/pull/103947

Issue: https://github.com/flutter/flutter/issues/102451

Manual engine roll to work around https://github.com/flutter/flutter/issues/104387

d882b2d123 Revert "Use CIPD to download prebuilt Dart SDKs (#33345)" (#33558)
4bff087248 Roll Skia from d3cbea4114aa to 86323276b2fc (4 revisions) (#33556)
80b183eab9 [Windows] Add textScaleFactor support (#33316)
9388aa1ee1 Roll Fuchsia Mac SDK from SmBoqSpQQ... to 1URI3xQBh... (#33554)
98be801b52 Roll Fuchsia Linux SDK from t9KwJZBWT... to KG9Y2q6J-... (#33553)
0c591bf62f Roll Skia from fb7f03aeac6e to d3cbea4114aa (1 revision) (#33550)
945cb2758b reduce the number of dependencies declared by flutter_frontend_server (#33520)
76137e82db Roll Fuchsia Mac SDK from yKCDVbBgS... to SmBoqSpQQ... (#33542)
dc49d18290 Roll Fuchsia Linux SDK from 3mdV9nX-U... to t9KwJZBWT... (#33541)
6a4c45aafa Roll Dart SDK from d3e96bbc3d87 to 7fa990079a0a (1 revision) (#33540)
5a3a0c1d35 Roll Skia from ade84dfd2ba5 to fb7f03aeac6e (1 revision) (#33539)
4db98a0795 Roll Fuchsia Mac SDK from 1QcM2qaSN... to yKCDVbBgS... (#33538)
f13d03c31a Roll Dart SDK from 708801716094 to d3e96bbc3d87 (1 revision) (#33537)
2d3affded7 Roll Fuchsia Linux SDK from asLtG1Pbw... to 3mdV9nX-U... (#33536)
dfa4724053 Roll Dart SDK from 90d5fdb9368b to 708801716094 (1 revision) (#33534)

* Add support for M3 AppBar 'Medium' and 'Large' types.

* Updates from review feedback.

* Updated from review feedback.