Fix renderSectionHeader callback of AgendaList

[vktrl]

Current implementation has an incorrect function signature for renderSectionHeader inherited from SectionList props. Only the title string is passed as an argument at runtime, but it's typed as { section: SectionListData<any, DefaultSectionT> }.

This PR does two things:

1. Fix the first argument type to match the runtime value
2. Add the full props of SectionList as the second argument for more flexibility while preserving backwards compatibility