Fix angry module LSP diagnostic (#6086)

### What was changed?
Improve LSP diagnostics, so instead of
<img width="278" alt="image"
src="https://github.com/user-attachments/assets/36977d46-a9e0-406c-af33-7a317426a767"
/>
the IDE shows
<img width="250" alt="image"
src="https://github.com/user-attachments/assets/87c9c5df-89a4-49ea-8882-8322881dad19"
/>

For the errors:
`not resolving module '_module' because there were errors in resolving
its nested module 'A'"`
`boolean literal used as if it had type int"`

### How has this been tested?
- Added an LSP test

<small>By submitting this pull request, I confirm that my contribution
is made under the terms of the [MIT
license](https://github.com/dafny-lang/dafny/blob/master/LICENSE.txt).</small>

Source/DafnyCore/AST/Modules/ModuleDefinition.cs

@@ -467,7 +467,7 @@ public bool Resolve(ModuleSignature sig, ModuleResolver resolver, string exportS
         if (!nestedModuleDecl.ModuleDef.SuccessfullyResolved) {
           if (!IsEssentiallyEmptyModuleBody()) {
             // say something only if this will cause any testing to be omitted
-            resolver.reporter.Error(MessageSource.Resolver, nestedModuleDecl,
+            resolver.reporter.Error(MessageSource.Resolver, nestedModuleDecl.NameNode,
               "not resolving module '{0}' because there were errors in resolving its nested module '{1}'", Name,
               nestedModuleDecl.Name);
           }

Source/DafnyLanguageServer.Test/Diagnostics/DiagnosticsTest.cs

@@ -18,6 +18,26 @@ namespace Microsoft.Dafny.LanguageServer.IntegrationTest.Synchronization {
   public class DiagnosticsTest : ClientBasedLanguageServerTest {
     private readonly string testFilesDirectory = Path.Combine(Directory.GetCurrentDirectory(), "Synchronization/TestFiles");
 
+    [Fact]
+    public async Task NestedModuleRange() {
+      var source = @"
+module A {
+  function A(x: int): int {
+    true
+  }
+  function B(x: int): int {
+    1
+  }
+}
+method Main() {
+}".TrimStart();
+      var documentItem = CreateAndOpenTestDocument(source);
+      var diagnostics1 = await GetLastDiagnostics(documentItem);
+      var startOrdered = diagnostics1.OrderBy(r => r.Range.Start).ToList();
+      Assert.Equal(new Range(0, 7, 0, 8), startOrdered[0].Range);
+      Assert.Equal(new Range(1, 2, 3, 3), startOrdered[1].Range);
+    }
+
     [Fact]
     public async Task ResolutionErrorMigration() {
       var source = @"module ResolutionError {