Add confirm prompt if turbo is available

[patriciomacadden]

In the past, the scaffold generator added a confirm prompt to the destroy button. This PR adds it back only if Turbo is available.

[patriciomacadden]

also adding cursor-pointer class to the destroy button as otherwise it'll show the normal cursor, which is odd for buttons.

[flavorjones]

@patriciomacadden Do we need to check if Turbo is available? What's the down side of always adding the data-turbo-confirm attribute?

It feels like unnecessary complexity, since I'm assuming that the attribute has no effect if Turbo is not present, but I'm not very familiar with turbo-rails so maybe I'm missing something.

Also, would you mind updating this PR to also include the destroy link merged from #461?

[patriciomacadden]

@flavorjones i don't think there's a downside of adding data-turbo-confirm if turbo isn't present. It would be only a generated attribute that won't be used by anyone, but i don't think it's a problem. I thought it was clearer this way, but I can remove the check. No problem.

I'll also add the styles merged in #461 .

[flavorjones]

woot!