[FIR LT] Get correct startOffset value for declarations with comments

#KT-56913 Fixed
#KT-56926 Fixed

compiler/testData/debug/stepping/comments.kt

@@ -0,0 +1,54 @@
+// FILE: test.kt
+
+// Single line comment
+fun box() {
+    A().foo()
+    A().bar()
+}
+
+/*
+ Multi
+ line
+
+ comment
+ */
+class A {
+    /**
+     * Doc
+     * comment
+     */
+
+
+    fun foo() {
+
+    }
+
+    // Single line comment 1
+
+    // Single line comment 2
+    fun bar() {
+
+    }
+}
+
+// EXPECTATIONS JVM JVM_IR
+// test.kt:5 box
+// test.kt:15 <init>
+// test.kt:5 box
+// test.kt:24 foo
+// test.kt:6 box
+// test.kt:15 <init>
+// test.kt:6 box
+// test.kt:31 bar
+// test.kt:7 box
+
+// EXPECTATIONS JS_IR
+// test.kt:5 box
+// test.kt:15 <init>
+// test.kt:5 box
+// test.kt:24 foo
+// test.kt:6 box
+// test.kt:15 <init>
+// test.kt:6 box
+// test.kt:31 bar
+// test.kt:7 box