reuse the function `get_crowd_groups`

coubeatczech/wordpress-crowd-plugin#2
hide group mapping inputs on focus out

coubeatczech/wordpress-crowd-plugin#2
change checked in option to selected

coubeatczech/wordpress-crowd-plugin#2
adjust height of the advanced column

Because there are more items in it.
coubeatczech/wordpress-crowd-plugin#2
save option only when the relevant mode is selected

coubeatczech/wordpress-crowd-plugin#2