Title: #5460: ipatests: use pexpect for controlling interactive command line utilities
This PR adds a tests-oriented wrapper for pexpect module
The pexpect module can be used for controlling and testing interactive command-line
programs. The wrapper adds testing-oriented features like logging and automatic process
termination and default check for process exit status.
Invocation of `ktutil` on systems with old version of `readline` is fixed using
Few tests in `test_adtrust_install` were refactored to utilize `pexpect` to improve the
tests and provide usage example.
To pull the PR as Git branch:
git remote add ghfreeipa https://github.com/freeipa/freeipa
git fetch ghfreeipa pull/5460/head:pr5460
git checkout pr5460