Restructure ListItemAccessControl types

[dcousens]

For an attempt at DRY, and trying to read these types, I have opted to merge the CreateListItemAccessControl, UpdateListItemAccessControl and DeleteListItemAccessControl types into the ListItemAccessControl type, as we have for other types in packages/core/src/types/config/access-control.ts.

This will help in scenarios where you might want to use ListItemAccessControl, but for example only need ListItemAccessControl<'create' | 'update'>.

I have additionally unpacked the KeystoneListsAPI and KeystoneDbAPI for future work, which were previously inlined into their respective index signature types.

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