[NI] Remove Nothing result type restriction in most cases

Make Nothing as result type not suitable only for if, when, try and ?: special functions.

compiler/testData/diagnostics/tests/when/kt9929.kt

@@ -1,5 +1,5 @@
 // !WITH_NEW_INFERENCE
-val test: Int = <!NI;TYPE_MISMATCH, NI;TYPE_MISMATCH!>if (true) {
+val test: Int = <!NI;TYPE_MISMATCH, NI;TYPE_MISMATCH, NI;TYPE_MISMATCH!>if (true) {
     when (2) {
         1 -> 1
         else -> <!OI;NULL_FOR_NONNULL_TYPE!>null<!>

compiler/testData/diagnostics/tests/when/whenAndLambdaWithExpectedType.kt

@@ -7,19 +7,19 @@ val test1: (String) -> Boolean =
 
 val test2: (String) -> Boolean =
         when {
-            true -> <!NI;TYPE_MISMATCH!>{{ true }}<!>
+            true -> {{ true }}
             else -> null!!
         }
 
 val test3: (String) -> Boolean =
         when {
-            true -> <!NI;TYPE_MISMATCH!>{ <!UNUSED_ANONYMOUS_PARAMETER!>s<!> -> true }<!>
+            true -> { <!UNUSED_ANONYMOUS_PARAMETER!>s<!> -> true }
             else -> null!!
         }
 
 val test4: (String) -> Boolean =
         when {
-            true -> <!NI;TYPE_MISMATCH!>{ <!OI;EXPECTED_PARAMETERS_NUMBER_MISMATCH!><!UNUSED_ANONYMOUS_PARAMETER!>s1<!>, <!OI;CANNOT_INFER_PARAMETER_TYPE, UNUSED_ANONYMOUS_PARAMETER!>s2<!><!> -> true }<!>
+            true -> <!NI;TYPE_MISMATCH!>{ <!EXPECTED_PARAMETERS_NUMBER_MISMATCH!><!UNUSED_ANONYMOUS_PARAMETER!>s1<!>, <!CANNOT_INFER_PARAMETER_TYPE, UNUSED_ANONYMOUS_PARAMETER!>s2<!><!> -> true }<!>
             else -> null!!
         }
 

compiler/testData/diagnostics/tests/when/whenWithNothingAndLambdas.kt

@@ -6,7 +6,7 @@ val <!OI;IMPLICIT_NOTHING_PROPERTY_TYPE!>test1<!> = when {
 }
 
 val test1a: () -> Boolean = when {
-    true -> <!NI;TYPE_MISMATCH!>{ { true } }<!>
+    true -> { { true } }
     else -> TODO()
 }
 
@@ -33,7 +33,7 @@ val <!OI;IMPLICIT_NOTHING_PROPERTY_TYPE!>test3<!> = when {
 }
 
 val test3a: () -> Boolean = when {
-    true -> <!NI;TYPE_MISMATCH!>{ { true } }<!>
-    true -> <!NI;TYPE_MISMATCH!>{ { true } }<!>
+    true -> { { true } }
+    true -> { { true } }
     else -> TODO()
 }