IArray extension methods

[brunnerant]

This is work in progress, it doesn't work yet (in particular, the test time out for some unknown reason).

[brunnerant]

Should I copy all the documentation from ArrayOps.scala to the extension methods that I added ?

[nicolasstucki]

Yes, that would be great

[nicolasstucki]

BTW, #7806 will move the IArray file. This should in theory not be a conflict as it does not change its contents.

[nicolasstucki]

The code LGTM. Just missing the documentation.

[brunnerant]

Ok, I will do it as soon as possible !

[brunnerant]

I just copied the comments from ArrayOps.scala (in Scala 2). Note that I only took the short description of the methods, not the entire documentation about the parameters and the return value.