66136 [versions] update to latest source span and roll engine to  4b8477d11573d233e6791204191c0090f733b05d (cla: yes, engine, team, tool, waiting for tree to go green)

66151 [flutter_tools] map file Uri to multi-root scheme if provided (cla: yes, tool)

66152 Added timeout for closing devfs sync http connections. (cla: yes, tool)

66156 [flutter_tools] fix bug where last build id parent folder is missing (cla: yes, tool, waiting for tree to go green)

66159 [flutter_tools] add EPERM to set of immediate exit errors (cla: yes, tool, waiting for tree to go green)