AB#128560 grid-export-error

[GhaziAlibi]

Description

Fixes the infinite spinner in the layout Filter tab when editing a nested resource / resources sub-grid field.

The frontend was building the meta introspection query from the field name (_sourcesMeta) instead of the resource's top-level query name (_allSourcesMeta), so the backend rejected it with a GraphQL validation error and the unhandled rejection left the loader stuck.

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)

How Has This Been Tested?

• Manual repro: opened a grid widget with a resources field (sources), edited the layout, opened the field's editor → Filter tab → confirmed the loader hangs and the network shows Cannot query field "_sourcesMeta".
• After the fix: same flow → Filter tab loads, sub-fields appear, can add a filter (e.g. staging_status = "Published") and save the layout.

Screenshots

Please include screenshots of this change. If this issue is only back-end related, and does not involve any visual change of the platform, you can skip this part.

Checklist:

• * I have set myself as assignee of the pull request
• * My code follows the style guidelines of this project
• * Linting does not generate new warnings
• * I have performed a self-review of my own code
• * I have put the ticket for review, adding the oort-frontend team to the list of reviewers
• * I have commented my code, particularly in hard-to-understand areas
• * I have put JSDoc comment in all required places
• * My changes generate no new warnings
• * I have included screenshots describing my changes if relevant
• * I have selected labels in the Pull Request, according to the changes with code brings
• I have made corresponding changes to the documentation ( if required )
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules

More explanation

https://www.loom.com/share/05a716d61b9744faaf51fb304c21d1e5?sid=f87cf896-582a-4f76-93ae-8ceed801b145