[FIR-IDE] Fix completion check for generic extensions

Generic candidate extensions are completed in partial mode
when there is not enough information for type parameter in return position.
Partial completion mode in single candidate resolver leads to unconditionally failing candidate.
Providing noExpectedType instead of null guarantees full completion.

idea/idea-completion/testData/basic/common/extensions/ParametrizedExpectedType.kt

@@ -0,0 +1,11 @@
+// FIR_COMPARISON
+class Generic<T>
+
+fun <A : String, B, C> Generic<A>.extension(arg: (A) -> B): B = TODO()
+
+fun test() {
+    val v = Generic<String>()
+    v.ext<caret>
+}
+
+// EXIST: extension