Feature Request: vm commands for Composer, PHP, and WP-CLI

[retlehs]

Summary

Add trellis vm commands that utilize trellis vm shell --workdir=<cwd> <command> for: composer, php, and wp

This would allow for more quickly executing Composer, PHP, and WP-CLI commands

Examples:

$ trellis vm composer install
$ trellis vm wp acorn optimize:clear
$ trellis vm php script.php