Support java.util.SequencedCollection added in Java 21

[ekrich]

See https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/util/SequencedCollection.html

Background
When testing https://github.com/ekrich/sconfig with Java 21 and Scala 3.3.4, it seems the the above class is needed at least for the code in this project.

I was unable to create a reproducer. I was unable to see the problem with Scala 2.12 or 2.13. See the following issue: ekrich/sconfig#398. The issue seems to be the code related to java.util.ArrayList which implements java.util.List which extends java.util.SequencedCollection on Java.

[sjrd]

Also: SequencedMap and SequencedSet.

See JEP 431 for a comprehensive list of the new interfaces and their retrofitting in the collection hierarchy.

[sjrd]

Closing as completed by #5075. Although that PR does not provide any of the methods of the new traits, it should be enough to avoid the linking issues mentioned in the issue description.

If the methods are desirable, feel free to open a separate issue.

[sjrd]

FTR, my WiP for the methods is available here:
main...sjrd:scala-js:ju-sequencedcollection

[ekrich]

Confirmed that Scala.js 1.18.1 fixes my issue.