3585 [connectivity_platform_interface] nnbd stable release (cla: yes, nnbd, p: connectivity, waiting for tree to go green)

3586 [shared_preferences] Bump version for NNBD stable (cla: yes, nnbd, p: shared_preferences)

3587 [battery] Bump platform version to NNBD stable (cla: yes, nnbd, p: battery)

3588 [connectivity_macos] move NNBD to stable (cla: yes, nnbd, p: connectivity, platform-macos, waiting for tree to go green)

3589 [sensors] Update to NNBD stable (cla: yes, nnbd, p: sensors)

3593 [cross_file] Stable null safety release (cla: yes, nnbd, p: cross_file)