DT-602: Reorganize Robo command directories

[danepowell]

The files containing BLT's Robo command classes are organized in a fairly inscrutable and anachronistic folder hierarchy that has persisted through several reorganizations of the command namespaces themselves.

For instance, the recipes namespace contains commands to intialize ACSF projects, CI projects, or multisite projects, but these are currently scattered among the Acsf, Ci, and Generate directories.

Ideally I think the folder hierarchy would match the command namespace hierarchy. Additionally, commands within each file should be namespaced correctly (for instance the drupal:install command is confusingly defined in BuildCommand.php rather than DrupalCommand.php).

Bonus points for a PHPCS rule or some other validation that enforces this organization going forward.

[mikemadison13]

+1 for this, there are definitely some commands that are impossible to find (and even if you do find them, they don't make a ton of sense where they are).