55829 allow changing the paint offset of a GlowingOverscrollIndicator (a: fidelity, a: quality, cla: yes, d: api docs, d: examples, documentation, f: material design, f: scrolling, framework, severe: new feature, waiting for tree to go green)

57838 Add sample code of  GestureDetector with no children (cla: yes, d: api docs, d: examples, documentation, f: gestures, framework, waiting for tree to go green)

58456 Update StandardCodec documentation with double alignment (cla: yes, documentation, framework, waiting for tree to go green)

59187 Support floating the header slivers of a NestedScrollView (a: annoyance, a: quality, cla: yes, customer: crowd, customer: quill (g3), d: api docs, d: examples, documentation, f: material design, f: scrolling, framework, waiting for tree to go green)