fix(frontend/Administration): sort columns of admin table correctly

Revisits USERS column accessor in the GROUPS table of /admin.
Revisits MANAGERS column accessor in the DATA PROVIDERS table of /admin.
Now the content of the columns is the actual lenght of the users array, not the array itself.
This is semantically more precise and also makes the column sort correctly.

Adds sortType: 'caseInsensitive' to the following columns:
* NAME column in GROUPS table of /admin
* NAME column in NODES table of /admin
* NAME column in DATA PROVIDERS table of /admin

Changes the way the STATUS column of DATA PROVIDERS table in /admin is sorted.
Now the boolean values the column is populated with are treated as numbers.
This is done by exploiting TS truthy and falsy expressions.