Bug 27247: Re-add highlighting to the quote editor

Bug 27247: Re-add highlighting to the quote editor

Caused by
  commmit 247dca306407ac9568344a0a37aca3bbcffc2468
  Bug 23013: Upgrade DataTables in the staff client

which removed

-tr.even.selected td {
-    background-color: #D3D3D3;
-}

There was no more highlighting when trying to delete an imported quote, as there was before
(see screenshot from the manual https://gitlab.com/koha-community/koha-manual/-/blob/master/source/images/tools/qotd/selectfordelete.png)

It was, however, possible to delete imported quotes, you just don't see which ones you are deleting.

Test plan:
1) Create a CSV with two columns first the name, then the quote (I've attached a CSV that I've done for testing purposes)
2) Go to Tools > Edit quotes for the QOTD feature
3) Click 'Import quotes'
4) Click 'Browse' and choose the CSV created earlier
5) Click on the id of a couple of quotes. Notice those lintes are highlighted

Signed-off-by: Lucas Gass <lucas@bywatersolutions.com>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>