FIR: fix some errors in local variable assignment analyzer

* wrong method was called from FirDataFlowAnalyzer.exitFunctionCall;
 * map from function to affected properties should be keyed by symbol,
   not FirFunction, as the latter may change;
 * arguments of `return` and assignment statements should be visited,
   as they may contain lambdas.

compiler/tests-spec/testData/diagnostics/notLinked/dfa/neg/18.fir.kt

@@ -1,69 +0,0 @@
-// !LANGUAGE: +NewInference
-// !DIAGNOSTICS: -UNUSED_EXPRESSION
-// SKIP_TXT
-
-/*
- * TESTCASE NUMBER: 1
- * ISSUES: KT-30826
- */
-fun case_1(x: Interface1?) {
-    var y = x
-    y as Interface2
-    val foo = {
-        <!DEBUG_INFO_EXPRESSION_TYPE("Interface1? & Interface1 & Interface2")!>y<!>.itest2()
-    }
-    y = null
-    foo()
-}
-
-/*
- * TESTCASE NUMBER: 2
- * ISSUES: KT-30826
- */
-fun case_2(x: Interface1?) {
-    var y = x
-    y as Interface2
-    val foo = fun () {
-        <!DEBUG_INFO_EXPRESSION_TYPE("Interface1? & Interface1 & Interface2")!>y<!>.itest2()
-    }
-    y = null
-    foo()
-}
-
-/*
- * TESTCASE NUMBER: 3
- * ISSUES: KT-30826
- */
-fun case_3(x: Interface1?) {
-    var y = x
-    y as Interface2
-    fun foo() {
-        <!DEBUG_INFO_EXPRESSION_TYPE("Interface1?"), SMARTCAST_IMPOSSIBLE!>y<!>.itest2()
-    }
-    y = null
-    foo()
-}
-
-// TESTCASE NUMBER: 4
-fun case_4(x: Interface1?) {
-    var y = x
-    y as Interface2
-    y = null
-    fun foo() {
-        <!DEBUG_INFO_EXPRESSION_TYPE("Interface1?")!>y<!>.<!UNRESOLVED_REFERENCE!>itest2<!>()
-    }
-    y = x
-    foo()
-}
-
-// TESTCASE NUMBER: 5
-fun case_5(x: Interface1?) {
-    var y = x
-    y as Interface2
-    y = null
-    fun foo() {
-        <!DEBUG_INFO_EXPRESSION_TYPE("Interface1?")!>y<!>.<!UNRESOLVED_REFERENCE!>itest2<!>()
-    }
-    y = x
-    foo()
-}

compiler/tests-spec/testData/diagnostics/notLinked/dfa/neg/18.kt

@@ -1,3 +1,4 @@
+// FIR_IDENTICAL
 // !LANGUAGE: +NewInference
 // !DIAGNOSTICS: -UNUSED_EXPRESSION
 // SKIP_TXT