Introduce plusElement and minusElement to disambiguate situations like List<List<T>> + List<T>

#KT-9992 Fixed

libraries/stdlib/src/generated/_Collections.kt

@@ -1599,6 +1599,13 @@ public operator fun <T> Iterable<T>.minus(elements: Sequence<T>): List<T> {
     return this.filterNot { it in other }
 }
 
+/**
+ * Returns a list containing all elements of the original collection without the first occurrence of the given [element].
+ */
+public fun <T> Iterable<T>.minusElement(element: T): List<T> {
+    return minus(element)
+}
+
 /**
  * Splits the original collection into pair of lists,
  * where *first* list contains elements for which [predicate] yielded `true`,
@@ -1706,6 +1713,20 @@ public operator fun <T> Iterable<T>.plus(elements: Sequence<T>): List<T> {
     return result
 }
 
+/**
+ * Returns a list containing all elements of the original collection and then the given [element].
+ */
+public fun <T> Collection<T>.plusElement(element: T): List<T> {
+    return plus(element)
+}
+
+/**
+ * Returns a list containing all elements of the original collection and then the given [element].
+ */
+public fun <T> Iterable<T>.plusElement(element: T): List<T> {
+    return plus(element)
+}
+
 /**
  * Returns a list of pairs built from elements of both collections with same indexes. List has length of shortest collection.
  */