feat: support variant in action row

[ahivert]

Summary

• Added support for action variants on inline changelist row actions.

Previously, row actions rendered outside of the dropdown via extra_options={"display_in_dropdown": False} always used the default button variant. Inline row actions now pass the configured ActionVariant to the button component, so variants such as DANGER, PRIMARY, or SUCCESS are rendered correctly.

• Updated the changelist row actions documentation with an inline row action example using variant=ActionVariant.DANGER.

Test plan

• Added a test covering an inline changelist row action with ActionVariant.DANGER.
• Verified the rendered changelist contains the row action label.
• Verified the rendered output contains the expected danger button styling.

Use of AI

AI was used for all changes done.