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 wp-cli#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