[JS BE] Make sourceMap generation more precise

- Don't produce mapping for closing bracket in case of expressionBody
 - Map Kt*Function declaration into corresponding js fun declaration
 - Update test data & add new test

js/js.translator/testData/lineNumbers/whileWithComplexCondition.kt

@@ -12,4 +12,4 @@ fun box() {
     }
 }
 
-// LINES: 13 5 5 4 2 2 3 5 5 8 8 * 3 4 9 3 11 11
+// LINES: 1 13 5 5 4 2 2 3 5 5 8 8 * 3 4 9 3 11 11