Fix data-turbo-confirm on <a> without data-turbo-method

[marcoroth]

The documentation in the "Requiring Confirmation for a Visit" section mentions the use of the [data-turbo-confirm] attribute on an <a> element to prompt a confirmation before executing a visit. An example is given as follows:

<a href="/articles" data-turbo-confirm="Do you want to leave this page?">Back to articles</a>

Prior to version v7.2.5, this functionality did not work unless the [data-turbo-method] attribute was also present on the link.

This pull request modifies the behavior so that [data-turbo-confirm] can now be used on links without the [data-turbo-method] attribute.

Resolves #943
Resolves #1264
Resolves #1296
Closes #1266

[seanpdoyle]

I agree with the tests and the underlying behavior here.

Having said that, I worry that the FormLinkClickObserver is an inappropriate candidate for supporting that behavior.

Would an <a> without [data-turbo-method] be treated as a typical Visit navigation?

In the absence of that attribute, what is directing the code to flow through this observer? Could confirmation be accommodated elsewhere, closer to a typical <a>-driven Visit?

[marcoroth]

Thanks @seanpdoyle, this is good feedback! You are right, this logic doesn't belong to the FormLinkClickObserver.

I pushed up a version where we check for the presence of the data-turbo-confirm attribute in the regular visit flow for links in Session.

Since confirmMethod was tied to FormSubmission I extracted it into a new Confirmation class which both the form flow and link flow now make use of. I like this a lot better!

[searls]

Seems weird that the documentation still says this is possible when the example cited doesn't actually work:

<a href="/articles" data-turbo-confirm="Do you want to leave this page?">Back to articles</a>

Just spent 15 minutes verifying it wasn't a problem in my turbo version or import maps setup

[marcoroth]

Let me get this rebased so we get a chance to get this this merged in

[marcoroth]

I just rebased this PR again, but I feel like this is not quite right anymore after the merged PR #1217 from @seanpdoyle. The new Turbo.config.forms.confirm config option doesn't quite fit the naming now, since the confirm method is also used on non-form elements here.

I'm wondering if we should either rename the config option or also use the Turbo.config.forms.confirm config option for the <a> tags.