Use a separate diagnostic for 'suspend fun' sequence

instead of reusing existing one, since existing one
is ERROR, and we cannot turn code red without deprecating
it with WARNING.
 #KT-49264

compiler/testData/diagnostics/testsWithStdLib/coroutines/nonModifierFormForBuiltInWithFun.fir.kt

@@ -0,0 +1,29 @@
+// SKIP_TXT
+
+infix fun Int.suspend(c: () -> Unit) { c() }
+
+fun bar() {
+    1 <!MODIFIER_FORM_FOR_NON_BUILT_IN_SUSPEND!>suspend<!> fun() {
+        println()
+    }
+
+    1 <!SYNTAX!>@Ann suspend fun()<!> {
+        println()
+    }
+
+    1 <!MODIFIER_FORM_FOR_NON_BUILT_IN_SUSPEND!>suspend<!> @Ann fun() {
+        println()
+    }
+}
+
+@Target(AnnotationTarget.EXPRESSION)
+@Retention(AnnotationRetention.SOURCE)
+annotation class Ann
+
+fun main(suspend: WLambdaInvoke) {
+    1 <!MODIFIER_FORM_FOR_NON_BUILT_IN_SUSPEND!>suspend<!> fun() {}
+}
+
+class WLambdaInvoke {
+    operator fun Int.invoke(l: () -> Unit) {}
+}

compiler/testData/diagnostics/testsWithStdLib/coroutines/nonModifierFormForBuiltInWithFun.kt

@@ -1,10 +1,9 @@
-// FIR_IDENTICAL
 // SKIP_TXT
 
 infix fun Int.suspend(c: () -> Unit) { c() }
 
 fun bar() {
-    1 <!MODIFIER_FORM_FOR_NON_BUILT_IN_SUSPEND!>suspend<!> fun() {
+    1 <!MODIFIER_FORM_FOR_NON_BUILT_IN_SUSPEND_FUN!>suspend<!> fun() {
         println()
     }
 
@@ -12,7 +11,7 @@ fun bar() {
         println()
     }
 
-    1 <!MODIFIER_FORM_FOR_NON_BUILT_IN_SUSPEND!>suspend<!> @Ann fun() {
+    1 <!MODIFIER_FORM_FOR_NON_BUILT_IN_SUSPEND_FUN!>suspend<!> @Ann fun() {
         println()
     }
 }
@@ -22,7 +21,7 @@ fun bar() {
 annotation class Ann
 
 fun main(suspend: WLambdaInvoke) {
-    1 <!MODIFIER_FORM_FOR_NON_BUILT_IN_SUSPEND!>suspend<!> fun() {}
+    1 <!MODIFIER_FORM_FOR_NON_BUILT_IN_SUSPEND_FUN!>suspend<!> fun() {}
 }
 
 class WLambdaInvoke {