MavenTargetLocation: use serialize for equals and hashCode

In the TargetPlatformPreferencePage, upon the Apply button, some target
definition containing some MavenTargetLocation always was rewritten to
it's .target file. This was because MavenTargetLocation.equals never
returned true for multiple reasons, starting with MavenTargetDependency
lacking an impl of equals().
Using serialize(), we can be sure to perform the equals check on any
relevant attribute, including deeply nested ones.

Beyond that, also use serialize() to implement hashCode().

org.eclipse.m2e.pde.target/META-INF/MANIFEST.MF

@@ -2,7 +2,7 @@ Manifest-Version: 1.0
 Bundle-ManifestVersion: 2
 Bundle-Name: M2E PDE Integration
 Bundle-SymbolicName: org.eclipse.m2e.pde.target;singleton:=true
-Bundle-Version: 2.0.500.qualifier
+Bundle-Version: 2.0.600.qualifier
 Automatic-Module-Name: org.eclipse.m2e.pde.target
 Bundle-RequiredExecutionEnvironment: JavaSE-17
 Require-Bundle: org.eclipse.core.runtime;bundle-version="[3.27.0,4.0.0)",

org.eclipse.m2e.pde.target/src/org/eclipse/m2e/pde/target/MavenTargetLocation.java

@@ -514,7 +514,7 @@ public String getLocation(boolean resolve) throws CoreException {
 
 	@Override
 	public int hashCode() {
-		return Objects.hash(roots, dependencyScopes, failedArtifacts, metadataMode);
+		return serialize().hashCode();
 	}
 
 	@Override
@@ -523,9 +523,8 @@ public boolean equals(Object obj) {
 			return true;
 		}
 		return obj instanceof MavenTargetLocation other //
-				&& Objects.equals(roots, other.roots)//
-				&& Objects.equals(dependencyScopes, other.dependencyScopes)
-				&& Objects.equals(failedArtifacts, other.failedArtifacts);
+				// check each and every relevant attribute, including nested ones
+				&& serialize().equals(other.serialize());
 	}
 
 	public boolean isIncludeSource() {