Migrate to analyzer Element2 APIs

[davidmorgan]

Migrate to element2 APIs, prepare as a prerelease.

build and build_resolvers both get a major version bump to version 3. Other packages that do not depend on the changes increase their version range to include 3. build_runner and build_runner_core keep a tight constraint onto build and build_resolvers so they now require 3.

Start using tight bounds in build_test because it depends on build/build_runner_core/build_runner internals and this will allow refactors to not break released build_test versions.

The plan is to release this as a dev release to allow generator authors to try it before the full release. It already works e2e with source_gen and built_value

dart-lang/source_gen#763
google/built_value.dart#1369

--there will need to be a dev release of source_gen next, to allow generators that use source_gen to try it.

[github-actions]

PR Health

[github-actions]

Package publishing

Package	Version	Status	Publish tag (post-merge)
package:build	3.0.0-dev.1	ready to publish	build-v3.0.0-dev.1
package:build_config	1.1.3-wip	WIP (no publish necessary)
package:build_daemon	4.0.5-wip	WIP (no publish necessary)
package:build_modules	5.0.15	ready to publish	build_modules-v5.0.15
package:build_resolvers	3.0.0-dev.1	ready to publish	build_resolvers-v3.0.0-dev.1
package:build_runner	2.6.0-dev.1	ready to publish	build_runner-v2.6.0-dev.1
package:build_runner_core	9.2.0-dev.1	ready to publish	build_runner_core-v9.2.0-dev.1
package:build_test	3.3.0-dev.1	ready to publish	build_test-v3.3.0-dev.1
package:build_web_compilers	4.2.0	ready to publish	build_web_compilers-v4.2.0
package:scratch_space	1.1.0	ready to publish	scratch_space-v1.1.0

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