Configurable width and height for REPL printing in 3.8

[mrdziuban]

The switch to pprint in the 3.8 REPL provides some nice improvements, but I would like to be able to change the default print width of 100 and height of 50, maybe with new settings like -Xrepl-print-width and -Xrepl-print-height.

@bishabosha also suggested in #24111 (comment) that the default width could reuse the -pagewidth if that would be preferable to a new option.