User accounts - sorting, filtering, exporting to Excel, more granular searching

Sort the accounts listed in the grid, like we would in the candidate grid;

Filter the accounts listed in the grid, like we would in the candidate grid;

Export (to excel) the accounts listed in the grid, like we would in the candidate grid;

Search by account type (role) in the search users screen. A new field would need to be added with a drop-down of all account types.