Introduce FirFunctionReturnTypeMismatchChecker

compiler/testData/diagnostics/tests/controlStructures/kt10717.fir.kt

@@ -1,21 +1,21 @@
 // !DIAGNOSTICS: -UNUSED_EXPRESSION -UNREACHABLE_CODE -UNUSED_PARAMETER -RETURN_NOT_ALLOWED
 
 fun test1() = run {
-    return "OK"
+    return <!RETURN_TYPE_MISMATCH!>"OK"<!>
 }
 
 fun test2() = run {
     fun local(): String {
         return ""
     }
-    return ""
+    return <!RETURN_TYPE_MISMATCH!>""<!>
 }
 
 inline fun <T, R> Iterable<T>.map(transform: (T) -> R): List<R> = null!!
 fun test3(a: List<String>, b: List<Int>) = a.map {
-    if (it.length == 3) return null
-    if (it.length == 4) return ""
-    if (it.length == 4) return 5
+    if (it.length == 3) return <!RETURN_TYPE_MISMATCH!>null<!>
+    if (it.length == 4) return <!RETURN_TYPE_MISMATCH!>""<!>
+    if (it.length == 4) return <!RETURN_TYPE_MISMATCH!>5<!>
     if (it.length == 4) return b
     1
 }
@@ -24,14 +24,14 @@ fun test4() = run {
     fun test5() {
         return
 
-        return@test4
+        <!RETURN_TYPE_MISMATCH!>return@test4<!>
 
-        return return@test4
+        return <!RETURN_TYPE_MISMATCH!>return@test4<!>
 
-        return fun() { return; return@test4 "" }
+        return <!RETURN_TYPE_MISMATCH!>fun() { return; return@test4 <!RETURN_TYPE_MISMATCH!>""<!> }<!>
     }
 
-    return
+    <!RETURN_TYPE_MISMATCH!>return<!>
     3
 }
 
@@ -43,5 +43,5 @@ val foo: Int
     }
 
 fun test(): Int = run {
-    return ""
+    return <!RETURN_TYPE_MISMATCH!>""<!>
 }