Use values iterator and update in map equality/hash

[jakemac53]

Initially I tried using entries instead of a values iterator, but that was surprisingly slow. This appears to be a good middle ground (see history of this comment for old results).

Hashing is about the same, but much faster for maps which don't have O(1) lookup. Equality is much faster.

Benchmarks before:

DeepCollectionQualityUnordered.equals(RunTime): 7427.29020979021 us.
DeepCollectionQualityUnordered.hash(RunTime): 217.8173707406213 us.
DeepCollectionQuality.equals(RunTime): 2653.23875 us.
DeepCollectionQuality.hash(RunTime): 178.1674653887114 us.

Benchmarks after:

DeepCollectionQualityUnordered.equals(RunTime): 4435.374 us.
DeepCollectionQualityUnordered.hash(RunTime): 212.8631545473818 us.
DeepCollectionQuality.equals(RunTime): 1989.1746626686656 us.
DeepCollectionQuality.hash(RunTime): 178.3396697902722 us.

[github-actions]

Package publishing

Package	Version	Status	Publish tag (post-merge)
package:characters	1.4.0	ready to publish	characters-v1.4.0
package:args	2.6.1-wip	WIP (no publish necessary)
package:async	2.12.0	already published at pub.dev
package:collection	1.19.1-wip	WIP (no publish necessary)
package:convert	3.1.2	already published at pub.dev
package:crypto	3.0.6	already published at pub.dev
package:fixnum	1.1.1	already published at pub.dev
package:logging	1.3.0	already published at pub.dev
package:os_detect	2.0.3-wip	WIP (no publish necessary)
package:path	1.9.1	already published at pub.dev
package:platform	3.1.6	already published at pub.dev
package:typed_data	1.4.0	already published at pub.dev

Documentation at https://github.com/dart-lang/ecosystem/wiki/Publishing-automation.

[github-actions]

PR Health

Breaking changes ✔️

Package	Change	Current Version	New Version	Needed Version	Looking good?
collection	None	1.19.1-wip	1.19.1-wip	1.19.1-wip	✔️

Changelog Entry ✔️

Package	Changed Files

Changes to files need to be accounted for in their respective changelogs.

Coverage ✔️

File	Coverage
pkgs/collection/lib/src/equality.dart	💚 89 %

This check for test coverage is informational (issues shown here will not fail the PR).

API leaks ✔️

The following packages contain symbols visible in the public API, but not exported by the library. Export these symbols or remove them from your publicly visible API.

Package	Leaked API symbols

License Headers ✔️

// Copyright (c) 2024, the Dart project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

Files
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[jakemac53]

cc @davidmorgan