Do not render declarations from other modules in diagnostic tests

Because PackageViewDescriptor may consist of several package fragments from
different modules (see LazyPackageViewDescriptorImpl#fragments), we now filter
out fragments from irrelevant modules before rendering them into the .txt

compiler/testData/diagnostics/tests/imports/CheckVisibility.txt

@@ -47,22 +47,6 @@ package k2 {
 package
 
 package k {
-
-    public final class A {
-        // -- Module: <m1> --
-    }
-
-    internal final class KInternal {
-        // -- Module: <m1> --
-    }
-
-    private final class KPrivate {
-        // -- Module: <m1> --
-    }
-
-    public final class KPublic {
-        // -- Module: <m1> --
-    }
 }
 
 package k2 {
@@ -70,5 +54,3 @@ package k2 {
 
 package k3 {
 }
-
-