ExpansionBarSection constructor
ExpansionBarSection({})
Initializes an ExpansionBarSection with optional title, subtitle, and header elements, along with text fallbacks and leading/trailing widgets.
The sliver is the required content body. backButton controls navigation behavior,
defaulting to never showing. initiallyExpanded sets the starting state (default true).
Leading and trailing lists allow custom icons or actions, with trailing dynamically
including an expand/collapse chevron based on sidebar expansion from ArcaneTheme.
Implementation
ExpansionBarSection(
{super.key,
this.backButton = BarBackButtonMode.never,
this.title,
required this.sliver,
this.subtitle,
this.header,
this.titleText,
this.subtitleText,
this.headerText,
this.leading = const [],
this.trailing = const [],
this.initiallyExpanded = true});