K2: Fix generic inference case with !! synthetic call

Result of the `checkNotNull` calls should always be a non-nullable
values.
The simplest idea how to acheive it is adding not-nullable Any bound
to the type parameter declaration.

Existing comment stating about impossibility of such bound seems to be
not 100% correct because it doesn't take into account presence of
definitely-non-nullable X & Any types that allow described case with
nullable generic.

^KT-55804 Fixed

compiler/testData/diagnostics/tests/inference/exclExclInference.fir.txt

@@ -0,0 +1,16 @@
+FILE: exclExclInference.fir.kt
+    public final fun foo(): R|kotlin/Unit| {
+        lval x: R|kotlin/String?|
+        R|<local>/x| = R|/materialize|<R|kotlin/String?|>()!!
+        R|<local>/x|.R|kotlin/String.length|
+    }
+    public final fun <E> materialize(): R|E| {
+        ^materialize R|kotlin/TODO|()
+    }
+    public final fun <F> test(f: R|F|): R|F & Any| {
+        ^test R|<local>/f|!!
+    }
+    public final fun main(): R|kotlin/Unit| {
+        R|/test|<R|kotlin/String|>(String()).R|kotlin/String.length|
+        R|/test|<R|kotlin/String?|>(Null(null)).R|kotlin/String.length|
+    }