[FIR] Implement ASSIGNMENT_TYPE_MISMATCH, RESULT_TYPE_MISMATCH diagnostics, fix tests

compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/OverrideGetterOnly.fir.kt

@@ -4,7 +4,7 @@ fun foo(o: JavaClass2) {
     useString(o.something)
     o.something = ""
     o.setSomething(1)
-    o.something = 1 // we generate extension property for JavaClass2 with more specific type
+    o.something = <!ASSIGNMENT_TYPE_MISMATCH!>1<!> // we generate extension property for JavaClass2 with more specific type
     o.something += "1"
 }
 
@@ -19,4 +19,4 @@ public class JavaClass1 {
 // FILE: JavaClass2.java
 public class JavaClass2 extends JavaClass1 {
     public String getSomething() { return ""; }
-}
+}