codegen-java: Support not annotating constructor parameters (#792)

Motivation:
Spring Boot configuration classes neither require nor benefit from annotating constructor parameters with their name.
The same is true for pkl-config-java configuration classes compiled with `-parameter`.

Changes:
- Change CLI parameter `--params-annotation` to accept a `none` value.
  This is recommended in https://clig.dev/#arguments-and-flags and is how the `-F` parameter of the `ssh` command works.
- Change `paramsAnnotation` property in Gradle plugin, CliJavaCodeGeneratorOptions, and JavaCodegenOptions as follows:
  - Change meaning of `null` from "generate org.pkl.java.config.mapper.Named annotations" to "do not generate annotations".
    This is a breaking change (only) affecting users who explicitly set the property to `null` instead of omitting it.
  - Change property default from `null` to:
    `null` if `generateSpringBootConfig` is `true` and `org.pkl.java.config.mapper.Named` otherwise
- add tests
- update docs of this and other codegen options

Result:
Generated code does not contain unnecessary annotations.

docs/modules/java-binding/partials/cli-codegen-options.adoc

@@ -26,7 +26,7 @@ Flag that indicates to generate config classes for use with Spring Boot.
 [%collapsible]
 ====
 Default: (not set) +
-Whether to make generated classes implement `java.io.Serializable`.
+Flag that indicates to generate classes that implement `java.io.Serializable`.
 ====
 
 .--rename