ENH: Add ndarray tile method

[jakirkham]

There is already a repeat method for ndarrays. It would be good for symmetry to have a tile method as well.

[charris]

Take a look at #7768. I'm embarrassed that after taking it over it is still unfinishec.

[eric-wieser]

@charris: I think this is just the "why does ndarray.X method not exist when ndarray.Y does, where np.X and np.Y are existing and similar" issue again. (like #8797)

[WarrenWeckesser]

After reviewing the linked issue about median, my conclusion is that the same arguments apply here. I'm closing the issue, but @jakirkham, if you still think tile should be a method, I won't complain if you reopen the issue and try again to make a case for adding it.