Features/WithGroupedHeadingRow

[VFAndrew]

1️⃣ Why should it be added? What are the benefits of this change?
Adds concern WithGroupedHeadingRow to allow import sheets to group data values in an array when multiple columns share the same header key

2️⃣ Does it contain multiple, unrelated changes? Please separate the PRs out.
No

3️⃣ Does it include tests, if possible?
Yes

4️⃣ Any drawbacks? Possible breaking changes?
No

5️⃣ Mark the following tasks as done:

• Checked the codebase to ensure that your feature doesn't already exist.
• Take note of the contributing guidelines.
• Checked the pull requests to ensure that another person hasn't already submitted a fix.
• Added tests to ensure against regression.
• Updated the changelog

6️⃣ Thanks for contributing! 🙌

[patrickbrouwers]

Thanks for the PR, looks good. Can you also update the changelog?

[VFAndrew]

Thanks for the PR, looks good. Can you also update the changelog?

Whoops, closed my previous PR to keep your package commit history as clean as possible and forgot to include the changelog again.

[VFAndrew]

@patrickbrouwers Should be good for further review now.

I also made WithGroupedHeaders concern an extension of WithHeadingRow to enforce the heading row being used. I believe that makes sense but let me know if I should revert that change.

Maybe I should update the concern to WithGroupedHeadingRow to imply this extension?

[patrickbrouwers]

I also made WithGroupedHeaders concern an extension of WithHeadingRow to enforce the heading row being used. I believe that makes sense but let me know if I should revert that change.

That's a good idea, nice!

Maybe I should update the concern to WithGroupedHeadingRow to imply this extension?

Yes, that sounds better, great suggestion!