FIR: Fix overload resolution for some invoke cases

Namely, it's about the cases when there are multiple variable candidates
with the same priority and all of them should be collected and compared

compiler/fir/analysis-tests/testData/resolveWithStdlib/problems/invokePriority.txt

@@ -74,6 +74,6 @@ FILE: invokePriority.kt
 
     }
     public final fun main(): R|kotlin/Unit| {
-        Q|E|.R|/E.Companion.f|.R|/E.f.invoke|()
+        Q|E|.<Ambiguity: f, [/E.f.invoke, kotlin/Function0.invoke]>#()
         Q|E.f|.R|/E.f.invoke|()
     }