[RHCLOUD-48734] Add traditional expandable row support to DataViewTable

[katarinazaprazna]

Summary

• Add support for traditional expandable rows
• Traditional expand renders a dedicated toggle column as the first column
• No breaking API changes: columnId on ExpandableContent changed from required to optional, existing consumers with columnId get identical compound behavior
• Add examples and documentation for both expand types

Test plan

• npm run test passes (11 tests in DataViewTableBasic)
• Docs dev server: expandable rows example renders with toggle column
• Docs dev server: compound expandable rows example renders unchanged
• Traditional expand: rows without content show empty toggle cell

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Closes RHCLOUD-48734

Assisted-by: Claude Code

[MariSvirik]

To be consistent with a simple expandable row pattern from PF,

1. remove grey background and
2. Change the orientation of the caret according to the new PF update (default facing down, opened facing up)
3. Follow this behaviour for the caret https://www.patternfly.org/components/table/react-demos/expandcollapse-all/ - grey background at the click and the hover
4. It would be great if you could add support for "Expand all" (caret in the column header section)

More technical issues consult with Patternfly team.

[karelhala]

Overall solid PR — clean separation of compound vs traditional expand, good test coverage, docs well-structured. Three inline comments.

[katarinazaprazna]

Thanks for catching those edge cases! I've applied the changes :)