FIR DFA: align FirLocalVariableAssignmentAnalyzer with the graph builder

I.e. maintain a set of seen lambdas where each marked as either "data
flow only" or "both data and control flow". The latter are truly
parallel with the function being analyzed, while the former have
technically already terminated, we just don't know the types inside them
because they may not have been analyzed yet.

compiler/testData/diagnostics/testsWithStdLib/smartcasts/lambdaInCallArgs.txt

@@ -5,4 +5,5 @@ public fun myRun(/*0*/ block: () -> kotlin.Unit): kotlin.Any?
 public fun test_1(): kotlin.Unit
 public fun test_2(): kotlin.Unit
 public fun test_3(): kotlin.Unit
+public fun test_4(): kotlin.Unit