fixup dynamic_rom
New 'os/attached_dataspace.h' utility

The new Attached_dataspace complements the existing Attached_*
utilities with a simple version that can be used with any kind of
dataspaces. It may be even useful as a common base type for the other
variants. For example, this patch simplifies Attached_rom_dataspace
and removes the Terminal::Client::Io_buffer.
xml_generator fixup: add attribute(long)
Infrastructure for posting status reports

This commit introduces the "Report" session interface and a simple
service to forward reports to the LOG service.

Fixes #1026
nitpicker: Report pointer position