FORMS-784: Fix for fields filtering for single row export option 3

[bcvesalink]

Description

The fix which adding the filtering fields upon the export for Option #3 Single row export

Types of changes

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

Checklist

• I have read the CONTRIBUTING doc
• I have checked that unit tests pass locally with my changes
• I have run the npm script lint on the frontend and backend
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation (if appropriate)
• I have approval from the product owner for the contribution in this pull request

Further comments

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[WalterMoar]

I found a small problem with datagrids: the number of columns for a datagrid only depends on the last submission. To reproduce:

1. Have a form with a datagrid containing a single text field

2. Submit with three rows in the datagrid, then export

3. Submit with one row in the datagrid, then export

Is it only looking at the final submission for the fields? I think it will need to look at all submissions, which may also fix #536

[bcvesalink]

I found a small problem with datagrids: the number of columns for a datagrid only depends on the last submission. To reproduce:

Have a form with a datagrid containing a single text field

Submit with three rows in the datagrid, then export #536

good call, looking into it

[WalterMoar]

Looks good and fixes GitHub Issue 536 too!

Tests failing