[FIR] Only track assignment nodes for uncaught exception edges in CFG

UncaughtExceptionPath edges are used to influence smart-casting within
catch and finally blocks. Previously these edges were added from every
node which could throw an exception. But only assignment nodes influence
smart-casts by resetting inference back to some less specific type.
Therefore, instead of tracking every possible node which could throw an
exception - even though almost every statement node can - only add edges
from assignment nodes to catch and finally blocks. This fixes many
missing exception cases and also reduces the total number of incoming
edges to catch and finally blocks.

#KT-56872 Fixed

compiler/testData/diagnostics/tests/controlFlowAnalysis/smartCastInCatch.kt

@@ -1,9 +1,14 @@
 // !SKIP_TXT
+// DUMP_CFG
+
+import kotlin.reflect.KClass
 
 fun exc(flag: Boolean) {
     if (flag) throw RuntimeException()
 }
 
+fun Any.notNull() = toString()
+
 fun test(flag: Boolean) {
     var x: Any?
     x = ""
@@ -19,3 +24,52 @@ fun test(flag: Boolean) {
         x.<!UNRESOLVED_REFERENCE!>inc<!>()
     }
 }
+
+fun testGetClassThrows() {
+    var x: KClass<String>? = String::class
+    x as KClass<String>
+    try {
+        <!UNUSED_VALUE!>x =<!> null
+        x = String::class
+    } catch (e: Throwable) {
+        // bad - get class call can throw
+        <!DEBUG_INFO_SMARTCAST!>x<!>.notNull()
+    }
+}
+
+fun testMemberReferenceThrows() {
+    var x: Any? = ""
+    x as Any
+    try {
+        <!UNUSED_VALUE!>x =<!> null
+        x = String::length
+    } catch (ex: Throwable) {
+        // bad - get callable reference throw
+        <!DEBUG_INFO_SMARTCAST!>x<!>.notNull()
+    }
+}
+
+fun testExceptionBeforeLambda() {
+    var x: String? = ""
+    x as String
+    try {
+        x = null
+        run { x = "" }
+    } catch (ex: Throwable) {
+        // bad - `run` could throw before running lambda
+        <!SMARTCAST_IMPOSSIBLE!>x<!>.notNull()
+    }
+}
+
+fun testExceptionWithinLocalFunction() {
+    var x: Any = ""
+    x as String
+    try {
+        fun local() {
+            x = 1
+        }
+    } catch (e: Exception) {
+        // bad - `local` could be run and reset smartcasting
+        <!SMARTCAST_IMPOSSIBLE!>x<!>.length
+    }
+}