When deleting a board w/ images, the image usage checking logic was not checking image collection fields. This could result in a nonexistent image lingering in a node.
We already handle single image fields correctly, it's only the image collection fields taht were affected.
This fixes the broken readiness checks introduced in the previous commit.
To support async batch generators, all of the validation of the generators needs to be async. This is problematic because a lot of the validation logic was in redux selectors, which are necessarily synchronous.
To resolve this, the readiness checks and related logic are restructured to be run async in response to redux state changes via `useEffect` (another option is to directly subscribe to redux store). These async functions then set some react state. The checks are debounced to prevent thrashing the UI.
See #7580 for more context about this issue.
Other changes:
- Fix a minor issue where empty collections were also checked against their min and max sizes, and errors were shown for all the checks. If a collection is empty, we don't need to do the min/max checks. If a collection is empty, we skip the other min/max checks and do not report those errors to the user.
- When a field is connected, do not attempt to check its value. This fixes an issue where collection fields with a connection could erroneously appear to be invalid.
- Improved error messages for batch nodes.
Board fields in the workflow editor now default to using the auto-add board by default.
**This is a change in behaviour - previously, we defaulted to no board (i.e. Uncategorized).**
There is some translation needed between the UI field values for a board and what the graph expects.
A "BoardField" is an object in the shape of `{board_id: string}`.
Valid board field values in the graph:
- undefined
- a BoardField
Value UI values and their mapping to the graph values:
- 'none' -> undefined
- 'auto' -> BoardField for the auto-add board, or if the auto-add board is Uncategorized, undefined
- undefined -> undefined (this is a fallback case with the new logic)
- a BoardField -> the same BoardField
