[Reference] settings element: expandable table

[Buckwich]

Closes #5183

• Depends on feat: support constraints in settings #5256
• Depends on feat: support conditional fields in settings #5253

Proposed Changes

Enable editing of arrays of objects with an expandable table

Known Issues

• A general issue with the settings modal where select all is not activated for the inputs: support Select All shortcut in settings fields #5306
• Settings are not saved if one field is invalid (even if its not shown): fixed in Improve constrained settings UX #5355

Checklist

To ensure you provided everything we need to look at your PR:

• Brief textual description of the changes present
• Visual demo attached
• Steps to try out present, i.e. using the @bpmn-io/sr tool
• Related issue linked via Closes {LINK_TO_ISSUE} or Related to {LINK_TO_ISSUE}

[Copilot]

Pull Request Overview

This PR introduces an "expandable table" form field type that enables editing arrays of objects through an interactive table interface. Users can add, remove, and expand rows to edit nested properties within each array element.

Key changes:

• Added expandable table field type with support for row and child properties
• Implemented table UI with expand/collapse functionality for editing nested data
• Added comprehensive test coverage for various scenarios including conditional fields and validation

Reviewed Changes

Copilot reviewed 5 out of 6 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
resources/plugins/test-client/client/TestClient.js	Adds example configuration for the new expandable table field type
client/src/plugins/settings/tests/SettingsFormSpec.js	Comprehensive test suite covering expandable table functionality
client/src/plugins/settings/SettingsPlugin.less	Styling for the expandable table component
client/src/plugins/settings/SettingsForm.js	Core implementation of the expandable table field array component
client/src/app/Settings.js	Updated type definitions to include the new expandable table type

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[Buckwich]

rebased onto develop, main change is the add button is now icon first

[Buckwich]

Marking draft as I think just reviewing #5375 is easier to review now in one go. But if you prefer to review this one just mark it ready again