Prepare for release.

[davidmorgan]

Release for #4143, and there's a nice pile of features/fixes along with it.

[github-actions]

PR Health

Changelog Entry ✔️

Package	Changed Files

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

[github-actions]

Package publishing

Package	Version	Status	Publish tag (post-merge)
package:build	3.0.2	ready to publish	build-v3.0.2
package:build_config	1.2.0	ready to publish	build_config-v1.2.0
package:build_daemon	4.0.5-wip	WIP (no publish necessary)
package:build_modules	5.0.16	already published at pub.dev
package:build_resolvers	3.0.2	ready to publish	build_resolvers-v3.0.2
package:build_runner	2.7.0	ready to publish	build_runner-v2.7.0
package:build_runner_core	9.3.0	ready to publish	build_runner_core-v9.3.0
package:build_test	3.3.2	ready to publish	build_test-v3.3.2
package:build_web_compilers	4.2.2	ready to publish	build_web_compilers-v4.2.2
package:scratch_space	1.1.0	already published at pub.dev

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