As a preparatory step for introducing the new block-client API, we have
to turn the 'Block::Connection' into a class template. The template
argument will be used to tie an application-defined job type to the
block connection.
Issue #3283
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.