Support pass-through args to the repl goal for ipython

[gauthamnair]

Fixes #3423

As discussed in #3423 (comment) we are implementing args at the goal-level but with a caveat that it is only available for some shells. In this PR, we only enable it for ipython. The repl will error out otherwise.

[gauthamnair]

Currently this work for an ipython shell, but does not work for a python shell. I am debugging why this might be.

[gauthamnair]

Ok, the issue with supplying arguments to the python repl has to do with two separate apparent issues with, upon closer debugging.

1. pex boot gets into an infinite loop when the pex has no entry point or script and is called with just an interpreter option, such as -q (this is easily fixable, will fix in pex, if it hasn't already been fixed in more recent versions).
2. pex boot does not seem to support the -i python flag, used to run some code or script but then drop into a shell. The script executes and a shell appears later but it does not have available the names that should be available at the end of running the script.

It is quite likely one or both of these already has a reported issue in pex, need to dig for them.

[gauthamnair]

• Interactive interpreter hangs if pex called with a python cli option pex-tool/pex#2248 is the hanging issue when only command line options are passed
• Unable to run a script in interactive mode -i pex-tool/pex#2249 is the inability to run a script in interactive mode off of a pex

[thejcannon]

Mind editing the title to be a bit more clear as to whats changing? 😄

[gauthamnair]

@thejcannon Changed it. :)

[stuhood]

Thanks a lot!

Sorry for the long delayed review.