Maybe add a display param (optional) to the abstract user data get() method

see https://github.com/gocodebox/lifterlms-convertkit/pull/15#issue-684132907 bullet #2

When saving a form basically we save checkbox/radio/select form field keys as meta value.

It might make sense to extend our api:
https://github.com/gocodebox/lifterlms/blob/trunk/includes/abstracts/llms.abstract.user.data.php#L171
with a new parameter display (default false), and add a new filter hook like here:
https://github.com/gocodebox/lifterlms/blob/trunk/includes/abstracts/llms.abstract.user.data.php#L172
`return apply_filters( 'llms_get_student_meta', $this->$key, $key, $display);`.
Will then add an hook in custom fields so that when `$display` is true and the $key is a custom field key it'll will look on how to display it (which basically it's, more or less, this https://github.com/gocodebox/lifterlms-custom-fields/blob/2.0.0/includes/class-llms-cf-fields-tracker.php#L562)