69000 [flutter_tools] implement safe file copy with multiple fallbacks (cla: yes, tool)

69016 [gen_l10n] Add base method code comments for improved discoverability (a: internationalization, cla: yes, tool, waiting for tree to go green)

69025 Reland: enable unnecessary_string_escapes and use_raw_strings (#68302) (a: internationalization, a: tests, cla: yes, f: cupertino, f: material design, framework, team, tool, waiting for tree to go green)

69033 [flutter_tools] update test platform to use buildInfo instead of mode + additional params (cla: yes, tool)

69041 Update null safe deps to prepare for the 2.12 sdk version (cla: yes, team, tool, waiting for tree to go green)