59025 Revert “Build iOS apps using Swift Packages” (cla: yes, d: examples, team, tool)

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)

59280 test flutter framework with null-safety (cla: yes, d: examples, team, waiting for tree to go green)

59896 gitignore .last_build_id file in the repo (cla: yes, d: examples, team, tool, waiting for tree to go green)

60222 Doc Updates (cla: yes, d: api docs, d: examples, documentation, f: scrolling, framework, waiting for tree to go green)