Health: catch addons installed in wrong folder

[mircobabini]

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Changes proposed in this Pull Request:

Sometimes you download an addon from github and you don't remove the -branch suffix.

This is from a conversation with Kim White; sometimes you are investigating a weird situation on a customer's site and you don't see that there's an addon installed with that wrong folder name, which prevents to be shown into PMPro > Add Ons > Installed list. Also prevents it to be updated.

Thanks to this PR, you will immediately see it into Site Health. Can be a starting point to show a warning into PMPro > Add Ons.

How to test the changes in this Pull Request:

1. Download a copy of an addon from github and install
2. Check Site Health > Info > PMPro section

Other information:

• Have you added an explanation of what your changes do and why you'd like us to include them?
• Have you successfully run tests with your changes locally?

[ideadude]

Is this the best name for this function.

We've been inconsistent on this in the past, but basically any new function we had should use snake case, e.g. pmpro_search_wrong_folder_name_addons().

But then I also think pmpro_find_wrong_folder_name_addons() might be more descriptive? Is there something even better? What other contexts are we going to use this? We only use this once, so we're abstracting a little earlier, but I think it's okay here. Let's just imagine how it might be used going forward and have the function name and doc block make the most sense.

Thanks!