Add more operations to FileIoC

[LnnrtS]

To support more operations on patch files in the wifi module, the filesystem abstraction first needs to implement those.
Required are

• creating and deleting directories
• moving files (should cover renaming)

Some more ideas to improve this abstraction layer:

• const_data and write_buffer are somewhat redundant. Why not just have the const version?
• foreach_file_with_ext could be replaced with a two step process: One lambda for the selection according to file infos and a second one for the action
• There could also be a dedicated struct with file information (name, size, timestamp)
• bool is sometimes used as an success indicator. That could be made explicit by giving it an extra type
• some methods are not yet required to return anything