PatternMatchingTypingVisitor:

rewrite type inference for 'when' using special constructs.
This fixes several type inference issues for 'when':
KT-9929, KT-9972, KT-10439, KT-10463
along with some other diagnostics-related issues.

compiler/testData/diagnostics/tests/controlStructures/kt10706.kt

@@ -4,8 +4,8 @@ fun fn(c: Char?): Any? =
         if (c == null) TODO()
         else when (<!DEBUG_INFO_SMARTCAST!>c<!>) {
             'a' -> when (<!DEBUG_INFO_SMARTCAST!>c<!>) {
-                'B' -> <!IMPLICIT_CAST_TO_ANY!>1<!>
-                'C' -> <!IMPLICIT_CAST_TO_ANY!>"sdf"<!>
+                'B' -> 1
+                'C' -> "sdf"
                 else -> TODO()
             }
             else -> TODO()