Use records instead of Immutables for plain value types

[abashev]

Follows #97: it builds on that PR's conventions.

Immutables generated eleven types. This turns the eight that are plain values into records and leaves the three that cannot be records as they stand.

What changes

• open-java-format-jdk-bootstrap. FormatterCliArgs and FormatterNativeImageArgs, the arguments of a formatter process, are records built through their constructors. The module no longer runs the Immutables processor.
• open-java-format. State's BreakState, LevelState and TokState, Level's SplitsBreaks, OpsBuilder's OpsOutput and InputMetadata are records. The call sites use constructors instead of builders and of(...); the accessors keep their names.

What stays on Immutables

• OpenOp and Break extend HasUniqueId, whose per-instance id orders the formatter's persistent collections, and a record cannot extend a class. They need the Doc hierarchy reworked first.
• State copies itself through its builder in about a dozen places. As a record each copy would list all ten components, or it would need a hand-written builder. It is created in the layout's hot loop, so that change wants a JMH measurement of its own.

Worth a look

• InputMetadata keeps @Immutable, which Error Prone now checks against the record's components; before, the generated class was excluded from analysis. That needed @Immutable on OpsBuilder.BlankLineWanted as well. Its two subclasses hold only an Optional<Boolean> and an ImmutableList<BreakTag>, and Error Prone verifies them.

Checked

• The 15,747 files of the JDK 21 sources format byte for byte as before: diff -rq of the trees formatted by the allJar of Replace palantir's Gradle plugins with plain Gradle #97's head, which main now holds, and of this branch.
• ./gradlew test: 1597 tests in :open-java-format and 10 in the IDEA plugin. With -PnativeImage=true, 60 in the Gradle plugin and 8 in jdk-bootstrap, whose FormatterServicesTest runs both changed services against a JDK and the native image.
• formatDiff through the released plugin.