#5974 reroll

1. docker exec and docker-compose exec provide an option to cleanly set the working directory before running a command
   => Use it instead and use cd <...> ; command-prefixing in vagrant/ssh cases

2. Using docker scheme, wp post update 1 - <<<foo didn't worked (issue passing stdin to command for docker-based WP instances #4972)

• Because STDOUT being a tty, -t is passed with no ability to inhibit this
• Because docker -i flag is necessary

=> As such:

• docker -i (--interactive) is introduced (with sensible autodetection)
• WP_CLI_DOCKER_NO_TTY and WP_CLI_DOCKER_NO_INTERACTIVE environment variables are introduced to optionally inhibit these respective flags

Special case to handle behat runs (see #5974)