Fixes https://github.com/flutter/flutter/issues/132990

Part of https://github.com/flutter/flutter/issues/127135

Part of https://github.com/flutter/flutter/issues/127135
Part of https://github.com/flutter/flutter/issues/125115

Originally reverted due to a misattributed hot reload benchmark
regression.

This reverts commit f5bce716.

This reverts commit c3de9015.

Also clean up messaging output by `flutter test` when `--start-paused` is provided.

* [flutter_tools] Add support for URI formats like ?line=x for "flutter test"

* Remove unnecessary function

* Handle parsing absolute paths on Windows

* Use Windows-style paths when running on Windows

* Fix paths in isFile

* Remove unnecessary clear

This reverts commit 254a796b.

Revert "Reland "Add --serve-observatory flag to run, attach, and test (#118402)" (#119529)" (#119729)

This reverts commit 7477d7ac.

* Reland "Add --serve-observatory flag to run, attach, and test (#118402)"

This reverts commit 86ab01d2.

* Fix flaky failures

* Fix VM service disappearing failure

This reverts commit 6cd4fa45.

This flag will allow for Observatory to be served by the VM service once it is disabled by default in the Dart SDK.

* removing default values for [reporter] and [timeout]]

* passing reporter arg to see tests pass

* added test to confirm TestCommand is not passing defaults

* add'l helper message for [reporter] arg

* default behavior for github actions + fixed tests

* removing github conditional for reporter + related test

* removing unused import

This reverts commit cb378edc.

* Randomize tests, exclude tests that fail with randomization.

* Disable some more tool tests

* opt out the flutter tool

* oops EOF

* fix import

* Update tool_backend.dart

* Update daemon_client.dart

* fix more

Split from #66776

Even if pub does not change the packge_config contents, it will still update a timestamp in one of the fields. This causes unnecessary rebuilds. To fix this, generate an additional file when running pub get that only contains the relevant fields and then update the KernelSnapshot rule to depend on it only.

flutter analyze was unconditionally using the cached dart-sdk for analysis, and was not running with the built SDK during local engine. This broke when trying to update the analyzer for null safety, since it required us to wait for the dart change to roll into the framework first.

This reverts commit 9ed3e5be.

flutter analyze was unconditionally using the cached dart-sdk for analysis, and was not running with the built SDK during local engine. This broke when trying to update the analyzer for null safety, since it required us to wait for the dart change to roll into the framework first.

Update the flutter and dart scripts' locking mechanism and follow_links function to be more robust and support more platforms.

This adds support for using mkdir as a fallback if the system doesn't have flock instead of using shlock, since shlock doesn't work on shared filesystems.

It also fixes a problem in the follow_links function where it failed when the link resolved to the root directory.