[IMRF-96] Add bash autocompletion to importify commands

[chshersh]

I heard that optparse-applicative supports bash autocompletion. It would be really great to add such support to importify.

[vrom911]

As a addition to the issue here is detailed info about completion in optparse-applicative: https://github.com/pcapriotti/optparse-applicative/wiki/Bash-Completion It says that by default, options and commands are always completed, but arguments completion should be enabled.