Optimize requests for Bitwarden access manager

[yannickhilber]

To store the GroupCollectionAccess group_name field for a collection, we need to perform an additional API request to retrieve the group_name (/public/groups/<group_id>) because the collection API response only gives the group_id.

This request is made for every groups that are assigned to a collection. The same group may be assigned to several collections which means that this API request is redundant.

We could create an dictionary of groups before calling the function get_collection() and lookup the dict to avoid redundant API requests.