chore: add hover background to table rows in admin pages

[BLumia]

This is a small QoL change to make the admin easier to do their management job. This makes knowing which row is the correct row to operate easier by simply checking the hover background, especially when they have a wide screen.

Sample:

The 2nd row is hovered, so before the admin clicks the "delete" button, they can know Magical8bitPlug2 is the one that the "delete" operation will be applied to.

[wxiaoguang]

Since they are still "ui table" elements, then they need this: https://fomantic-ui.com/collections/table.html#selectable-row

And we can't use .admin .table>tbody>tr:hover for "all" tables, it is too broad and not every table needs that "hover highlight".

[wxiaoguang]

And we can't use .admin .table>tbody>tr:hover for "all" tables, it is too broad and not every table needs that "hover highlight".

For example, at least, you broke this table:

[BLumia]

Since they are still "ui table" elements, then they need this:

The selectable class somehow doesn't work as intended while my testing. Will look into it later (we might need to update table.css to add support for selectable?).

And we can't use .admin .table>tbody>tr:hover for "all" tables, it is too broad

I agree. I added .admin to make the scope limited to tables on admin pages, but seems still too board because I previously didn't notice:

For example, at least, you broke this table:

Yeah, sorry I didn't notice that before.

I'll convert this PR as WIP to address the issue later.

[BLumia]

Let's move to #35072 since it involves change related to table.css, and other non-admin pages can get benefit from the change (to make use of the selectable css class) too.