Refactor redirects edit view to CBV

[rohitsrma]

In this PR I've converted redirects edit view from FBV to CBV as a part of #8365 .

[squash-labs]

Manage this branch in Squash

Test this branch here: https://rohitsrmarefactor-redirects-ed-k370b.squash.io

[laymonage]

Thanks! This is a good start, but there are a few things missing and some that could be improved. Some of them are things we've discussed before, so I highly suggest re-reviewing your previous PRs to avoid the same mistakes – which can help us move faster 😄

[rohitsrma]

Thanks @laymonage, I've made the changes. And, I'm really sorry for making the same mistakes again. I'll make sure not to do them again in the future.

[laymonage]

One small thing remaining (enabling breadcrumbs), but otherwise this looks good to me! I'll add the breadcrumbs myself and merge. Thanks, and sorry if my previous comment was a bit harsh!

[laymonage]

We can now show the breadcrumbs

Suggested change

	error_message = gettext_lazy("The redirect could not be saved due to errors.")
	error_message = gettext_lazy("The redirect could not be saved due to errors.")
	header_icon = "redirect"
	_show_breadcrumbs = True

[laymonage]

Thanks! Looks like this also resolves an issue where the error message for duplicate redirects is rendered awkwardly on the page, so that's great!

Before

After

Note: this issue still exists in the create view though, but that's a separate task.