Update help service to account for all `TypeDeclarationSyntax`...

Update help service to account for all `TypeDeclarationSyntax` (namespace+record+struct) as partial type (#48095)

src/VisualStudio/CSharp/Impl/LanguageService/CSharpHelpContextService.cs

@@ -284,7 +284,7 @@ private static bool TryGetTextForContextualKeyword(SyntaxToken token, out string
                             text = "partialmethod_CSharpKeyword";
                             return true;
                         }
-                        else if (token.Parent.GetAncestorOrThis<ClassDeclarationSyntax>() != null)
+                        else if (token.Parent.GetAncestorOrThis<TypeDeclarationSyntax>() != null)
                         {
                             text = "partialtype_CSharpKeyword";
                             return true;

src/VisualStudio/CSharp/Test/F1Help/F1HelpTests.cs

@@ -164,7 +164,7 @@ void goo()
         }
 
         [Fact, Trait(Traits.Feature, Traits.Features.F1Help)]
-        public async Task TestPartialType()
+        public async Task TestClassPartialType()
         {
             await Test_KeywordAsync(
 @"part[||]ial class C
@@ -174,7 +174,27 @@ public async Task TestPartialType()
         }
 
         [Fact, Trait(Traits.Feature, Traits.Features.F1Help)]
-        public async Task TestPartialMethod()
+        public async Task TestRecordPartialType()
+        {
+            await Test_KeywordAsync(
+@"part[||]ial record C
+{
+    partial void goo();
+}", "partialtype");
+        }
+
+        [Fact, Trait(Traits.Feature, Traits.Features.F1Help)]
+        public async Task TestRecordWithPrimaryConstructorPartialType()
+        {
+            await Test_KeywordAsync(
+@"part[||]ial record C(string S)
+{
+    partial void goo();
+}", "partialtype");
+        }
+
+        [Fact, Trait(Traits.Feature, Traits.Features.F1Help)]
+        public async Task TestPartialMethodInClass()
         {
             await Test_KeywordAsync(
 @"partial class C
@@ -183,6 +203,16 @@ public async Task TestPartialMethod()
 }", "partialmethod");
         }
 
+        [Fact, Trait(Traits.Feature, Traits.Features.F1Help)]
+        public async Task TestPartialMethodInRecord()
+        {
+            await Test_KeywordAsync(
+@"partial record C
+{
+    par[||]tial void goo();
+}", "partialmethod");
+        }
+
         [Fact, Trait(Traits.Feature, Traits.Features.F1Help)]
         public async Task TestExtendedPartialMethod()
         {