API Remove GraphQL

[emteknetnz]

Issue silverstripe/silverstripe-admin#1799

[GuySartorelli]

Few problems found while testing edge cases:

1. It seems like list view in the asset admin isn't using thumbnails. If I delete the thumbnail variants and then view the list view, I still see the image. If I right click on it and view image in new tab, it's the original full resolution image.
2. If AssetAdminOpen::apiRead() throws a json error, the asset admin doesn't load correctly and I see this in the dev console (yes it does just end abruptly - there's no more info other than a js stack trace):

   Uncaught (in promise) Error: 
   

3. if AssetAdmin::apiReadDescendantCounts() throws a json error, the confirm deletion modal is stuck loading with the same error as above in the dev console

I stopped checking at that point - it seems likely that all of the endpoints suffer from similar problems.
I didn't check elemental, but suspect it would probably have the same type of problems.

[emteknetnz]

It seems like list view in the asset admin isn't using thumbnails. If I delete the thumbnail variants and then view the list view, I still see the image. If I right click on it and view image in new tab, it's the original full resolution image.

Replicated this on 5.2, so looks like it's an existing issue

[GuySartorelli]

The new json error handling is great!

Found one problem when testing this time around.

Cannot cancel deleting a file

1. Upload a file.
2. Select the file.
3. Click the ... button
4. Click delete
5. Try to cancel the modal (it won't go away, and there's no errors in the console, no network requests, nothing)

The fact this wasn't caught by behat means we are missing a test scenario for this.

[emteknetnz]

Have fixed and added behat tests for cancelling and closing the modal

[GuySartorelli]

LGTM, works as expected locally.