Fix issue with user breadcrumbs

[jtapia]

Issue

• Breadcrumbs displays invalid emails modifying users  #3149

Preview

[jacobherrington]

@jtapia thanks for making this PR! 👍

I think this works, but do we feel like the real problem is displaying the wrong information or using an instance variable instead of the AR object? Would like your opinion @kennyadsl.

[kennyadsl]

This could be a solution (I'm wondering if using only @user.email_was without any if fixes the issue as well since I think it always returns the right email) anyway I think this issue could be present in several other admin pages and we should come up with a more robust long-term solution.

I'm taking a look at https://github.com/weppos/breadcrumbs_on_rails which is old and unmaintend but it's very few lines of code that we could add to solidus easily maybe. It provides an interface in the controller to set breadcrumbs, this way we could maybe define breadcrumbs before calling the update_attributes that makes the instance dirty? How does it play with ResourceController? Maybe worth exploring a little bit more.

[tvdeyen]

I like this simple fix for the edge case reported in #3149

Thanks

[ericsaupe]

Thanks!

[aldesantis]

@jtapia would like to get this in. Could you rebase?

[jtapia]

@aldesantis done

[aldesantis]

@jtapia thanks!