Setting AbsoluteLayout using Mattise in Gradle project results in UnsupportedOperationException

### Apache NetBeans version

Apache NetBeans 28 latest daily build

### What happened

IDE shows java.lang.UnsupportedOperationException editing JPanelForm with Matisse editor in Gradle project.
Also entire IDE window is blinks

### Language / Project Type / NetBeans Component

Matisse editor in Gradle project

### How to reproduce

Using IDE dev build: Apache NetBeans IDE DEV (Build dev-0216ca48bb4c1085270edc250b8c1d20f3cb0895)
Create new simple Gradle project
Add to project Simple JFrame or JPanel form
In Form editor invoke context menu and select Set Layout -> Absolute Layout
IDE blinks and Exception is thrown:
```
java.lang.UnsupportedOperationException: Project in D:\Work Files\NetBeans Projects\gradleproject1\app of class org.netbeans.modules.gradle.NbGradleProjectImpl has neither a ProjectClassPathModifierImplementation nor a ProjectClassPathExtender in its lookup
at org.netbeans.api.java.project.classpath.ProjectClassPathModifier.findExtensible(ProjectClassPathModifier.java:424)
at org.netbeans.api.java.project.classpath.ProjectClassPathModifier.addLibraries(ProjectClassPathModifier.java:82)
at org.netbeans.modules.nbform.project.ClassSourceResolver$LibraryEntry.addToProjectClassPath(ClassSourceResolver.java:208)
at org.netbeans.modules.form.project.ClassSource.addToProjectClassPath(ClassSource.java:91)
at org.netbeans.modules.form.project.ClassPathUtils$2.run(ClassPathUtils.java:245)
at org.netbeans.modules.progress.ui.RunOffEDTImpl$ProgressBackgroundRunner.runBackground(RunOffEDTImpl.java:465)
at org.netbeans.modules.progress.ui.AbstractWindowRunner.call(AbstractWindowRunner.java:86)
at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
at org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:1403)
at org.netbeans.modules.openide.util.GlobalLookup.execute(GlobalLookup.java:45)
at org.openide.util.lookup.Lookups.executeWith(Lookups.java:287)
at org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:2018)
Caused: java.util.concurrent.ExecutionException
at java.base/java.util.concurrent.FutureTask.report(FutureTask.java:122)
at java.base/java.util.concurrent.FutureTask.get(FutureTask.java:191)
[catch] at org.netbeans.modules.progress.ui.RunOffEDTImpl.showProgressDialogAndRun(RunOffEDTImpl.java:361)
at org.netbeans.api.progress.BaseProgressUtils.showProgressDialogAndRun(BaseProgressUtils.java:189)
at org.netbeans.api.progress.ProgressUtils.showProgressDialogAndRun(ProgressUtils.java:220)
at org.netbeans.modules.form.project.ClassPathUtils.updateProject(ClassPathUtils.java:241)
at org.netbeans.modules.form.project.ClassPathUtils.updateProject(ClassPathUtils.java:213)
at org.netbeans.modules.form.MetaComponentCreator.prepareClass(MetaComponentCreator.java:1414)
at org.netbeans.modules.form.MetaComponentCreator.createComponent(MetaComponentCreator.java:120)
at org.netbeans.modules.form.MetaComponentCreator.createComponent(MetaComponentCreator.java:112)
at org.netbeans.modules.form.MetaComponentCreator.createComponent(MetaComponentCreator.java:91)
at org.netbeans.modules.form.actions.SelectLayoutAction$LayoutActionListener.actionPerformed(SelectLayoutAction.java:274)

```

### Did this work correctly in an earlier version?

No / Don't know

### Operating System

Windows 10 version 10.0 running on amd64; UTF-8; ru_RU (nb)

### JDK

Java: 18.0.2; Java HotSpot(TM) 64-Bit Server VM 18.0.2+9-61

### Apache NetBeans packaging

Own source build

### Anything else

Same functionality works for Ant or Maven based projects. Invoking same command for maven projects shows 'Update classpath' progress popup and also adds AbsoluteLayout dependency to project dependencies

### Are you willing to submit a pull request?

No

Reproduce the failure by selecting Set Layout → Absolute Layout in a Gradle-based Matisse form, then start with ClassSourceResolver.java, ClassPathUtils.java, and the ProjectClassPathModifier stack-trace path. Compare the Gradle behavior with the working Ant and Maven flows; done means the layout action completes without the exception or IDE blinking and handles the dependency as expected.

Written by the indexing model from the issue text.