ILVerify after kept member validation (#99914)

- ILVerify will fail due to members not being kept, so to make the
  errors more informative, run kept member validation first, then
  ILVerify

src/tools/illink/test/Mono.Linker.Tests/TestCasesRunner/ResultChecker.cs

@@ -101,6 +101,7 @@ public virtual void Check (TrimmedTestCaseResult linkResult)
 					if (!HasActiveSkipKeptItemsValidationAttribute(linkResult.TestCase.FindTypeDefinition (original))) {
 						CreateAssemblyChecker (original, linked, linkResult).Verify ();
 					}
+					CreateILChecker ().Check(linkResult, original);
 				}
 
 				VerifyLinkingOfOtherAssemblies (original);
@@ -279,7 +280,6 @@ protected virtual void AdditionalChecking (TrimmedTestCaseResult linkResult, Ass
 
 		protected virtual void InitialChecking (TrimmedTestCaseResult linkResult, AssemblyDefinition original, AssemblyDefinition linked)
 		{
-			CreateILChecker ().Check(linkResult, original);
 			ValidateTypeRefsHaveValidAssemblyRefs (linked);
 		}