Adopt data structures to Java 21 changes

[PhilippWendler]

In Java 21 the collections API got some extensions, and once this project requires Java 21, we can make use of them.

Parts of this are:

• Implement SequencedCollection.getLast() directly in PersistentLinkedList. The default implementation is unnecessarily costly (traverses the list twice).
• Add all new modifying methods from Sequenced* to the Persistent* interfaces and mark them as deprecated and @DoNotCall.
• Implement SequencedMap.sequenced* methods directly such that there is no need for the default implementation with its additional indirection.
• Go through all the new interfaces and methods and check whether there are any more cases where a direct implementation makes sense.