Fix empty JaCoCo aggregate report by adding dedicated reporting module

The JaCoCo aggregate report was empty because the aggregator POM lacked
dependencies on the modules it was supposed to report on.

This change introduces a dedicated `org.moreunit.report` module that
handles the aggregation by explicitly depending on both the core
functional modules and their respective test suites. This ensures
JaCoCo can locate all classes, sources, and execution data.

The aggregate report is still output to the location expected by the CI
workflow: `org.moreunit.build/target/site/jacoco-aggregate/jacoco.xml`.

Changes:
- Created `org.moreunit.report/pom.xml` with coverage aggregation logic
  and dependencies on code and test modules.
- Registered the new module in `org.moreunit.build/pom.xml`.
- Removed the non-functional `report-aggregate` goal from the aggregator POM.

Co-authored-by: RoiSoleil <3462260+RoiSoleil@users.noreply.github.com>

Author: google-labs-jules[bot]

org.moreunit.report/pom.xml

@@ -34,6 +34,26 @@
           <artifactId>org.moreunit.mock</artifactId>
           <version>${project.version}</version>
         </dependency>
+        <dependency>
+          <groupId>org.moreunit</groupId>
+          <artifactId>org.moreunit.core.test</artifactId>
+          <version>${project.version}</version>
+        </dependency>
+        <dependency>
+          <groupId>org.moreunit</groupId>
+          <artifactId>org.moreunit.mock.test</artifactId>
+          <version>${project.version}</version>
+        </dependency>
+        <dependency>
+          <groupId>org.moreunit</groupId>
+          <artifactId>org.moreunit.swtbot.test</artifactId>
+          <version>${project.version}</version>
+        </dependency>
+        <dependency>
+          <groupId>org.moreunit.plugins</groupId>
+          <artifactId>org.moreunit.test</artifactId>
+          <version>${project.version}</version>
+        </dependency>
       </dependencies>
       <build>
         <plugins>