This commit applies the transition from the "Input" session to the "Event"
session to the event-filtering mechansim. The functionality of the
input_filter is now provided by the event_filter. The event filter
requests only one "Event" session as destination for the filter result,
which is usually routed to the nitpicker GUI server. It provides an
"Event" service to which any number of event sources can connect.
The configuration of the filter chain remains almost the same. Only the
declaration of the <input> nodes is no longer needed. Instead, the
configuration must specify <policy> nodes, which define the mapping of
"Event" clients (event sources) to the inputs used in the filter chain.
The patch adjusts all uses of the nitpicker GUI server accordingly such
that the event filter reports events to nitpicker's event service
instead of having nitpicker request an "Input" session. This dissolves
the dependency of nitpicker from input drivers.
Issue #3827
This patch removes the former use of ram_fs, fs_rom, and fs_report from
the subsystem and uses a report_rom instead. The fs-based reporting was
introduced to accommodate automatically instantiated usb_block drivers,
which turned out to be impractical for the sculpt scenario.
This is a drivers subsystem that starts the most fundamental
(framebuffer, input, block) device drivers dynamically, depending on the
runtime-detected devices. The discovered block devices are reported
as a "block_devices" report.
