[DX] Add a `project_get_info` helper function.

I thought of this while filing #2384...

I was thinking something like project_get_info($project_name, $property = NULL) that would auto-detect project type (from the .info file or the system table?). If $property is omitted, then an array of all the project info would be returned (keyed by property), else the specific property defined in $property. This would allow us to get a specific project property like this:

$human_readable_name = project_get_info('devel', 'name');

...instead of this:

$module_info = system_get_info('module', 'devel');
$human_readable_name = $module_info['name'];

...while still being able to do things like this:

$module_info = project_get_info('devel');
$human_readable_name = $module_info['name'];