Add namespaced WPCLI command for managing schemas

[borkweb]

It'd be rad to have some sort of auto-namespaced WPCLI commands for schema management

Here are some braindump notes:

wp {namespace}:schema help (list the tables)
wp {namespace}:schema {table} {up|down|drop|version}

wp tec:schema tec_events up

// Maybe build the namespace from the base namespace of the plugin that is consuming it.
$prefix = str_replace( '\\', '-', __NAMESPACE__ );

apply_filters( 'stellarwp_schema_wpcli_namespace', $prefix, __NAMESPACE__ );

wp tribe-pue:schema

[borkweb]

It might be a good idea to create a separate ultra-tiny library that does the namespace prefixing for WPCLI commands, because I imagine we'll need to do this more than once.