[FIR] Add diagnostic collector component that collects diagnostics from error nodes

compiler/frontend/src/org/jetbrains/kotlin/diagnostics/DiagnosticFactory0.java

@@ -25,10 +25,12 @@ public class DiagnosticFactory0<E extends PsiElement> extends DiagnosticFactoryW
         super(severity, positioningStrategy);
     }
 
+    @NotNull
     public static <T extends PsiElement> DiagnosticFactory0<T> create(Severity severity) {
         return create(severity, PositioningStrategies.DEFAULT);
     }
 
+    @NotNull
     public static <T extends PsiElement> DiagnosticFactory0<T> create(Severity severity, PositioningStrategy<? super T> positioningStrategy) {
         return new DiagnosticFactory0<>(severity, positioningStrategy);
     }

compiler/frontend/src/org/jetbrains/kotlin/diagnostics/DiagnosticFactory1.java

@@ -29,10 +29,12 @@ public class DiagnosticFactory1<E extends PsiElement, A> extends DiagnosticFacto
         super(severity, positioningStrategy);
     }
 
+    @NotNull
     public static <T extends PsiElement, A> DiagnosticFactory1<T, A> create(Severity severity, PositioningStrategy<? super T> positioningStrategy) {
         return new DiagnosticFactory1<>(severity, positioningStrategy);
     }
 
+    @NotNull
     public static <T extends PsiElement, A> DiagnosticFactory1<T, A> create(Severity severity) {
         return create(severity, PositioningStrategies.DEFAULT);
     }

compiler/frontend/src/org/jetbrains/kotlin/diagnostics/DiagnosticFactory2.java

@@ -30,10 +30,12 @@ public class DiagnosticFactory2<E extends PsiElement, A, B> extends DiagnosticFa
         super(severity, positioningStrategy);
     }
 
+    @NotNull
     public static <T extends PsiElement, A, B> DiagnosticFactory2<T, A, B> create(Severity severity, PositioningStrategy<? super T> positioningStrategy) {
         return new DiagnosticFactory2<>(severity, positioningStrategy);
     }
 
+    @NotNull
     public static <T extends PsiElement, A, B> DiagnosticFactory2<T, A, B> create(Severity severity) {
         return new DiagnosticFactory2<>(severity, PositioningStrategies.DEFAULT);
     }

compiler/frontend/src/org/jetbrains/kotlin/diagnostics/DiagnosticFactory3.java

@@ -25,10 +25,12 @@ public class DiagnosticFactory3<E extends PsiElement, A, B, C> extends Diagnosti
         super(severity, positioningStrategy);
     }
 
+    @NotNull
     public static <T extends PsiElement, A, B, C> DiagnosticFactory3<T, A, B, C> create(Severity severity) {
         return create(severity, PositioningStrategies.DEFAULT);
     }
 
+    @NotNull
     public static <T extends PsiElement, A, B, C> DiagnosticFactory3<T, A, B, C> create(Severity severity, PositioningStrategy<? super T> positioningStrategy) {
         return new DiagnosticFactory3<>(severity, positioningStrategy);
     }