Should be able to delete plugins

[taylortom]

Now that we can delete assets, the omission of this feature is much more noticeable.

Related forum posts:
https://community.adaptlearning.org/mod/forum/discuss.php?d=1013
https://community.adaptlearning.org/mod/forum/discuss.php?d=965

[brian-learningpool]

Implementation of this will probably involve a 'soft' delete, to ensure that courses which use the deleted plugin still build and preview ok. This is how asset deletion works right now.

[taylortom]

I think that's fine as a partial fix

[canstudios-nicolaw]

We have a version of plugin delete working on our adapt which we would like to give back to the community. At the moment, it only lets you delete the plugin if it isn't in use by any courses, if it is used in courses it lists the courses and the course owners.

I will assign this issue to myself for now and we can give this back soon (I won't add it to the loose ends milestone right now as I don't want to keep growing that milestone and adding features to test).

[taylortom]

I'd like to also put together a similar fix for asset deletion, so if we can decide on a strategy (the above sounds fine), then we should tackle that one too 😄