This has KString, KBuffer, DoubleBuffer, KBufferBuilder, IOWindow,
UserOrKernelBuffer and ScopedCritical classes being moved to the
Kernel/Library subdirectory.
Also, move the panic and assertions handling code to that directory.
While doing this, we can also just return a normal RefPtr instead of a
LockRefPtr, because we create these channels when initializing an audio
controller, and never change the pointer in AudioController instances
after their initialization, hence no locking is necessary.
Instead of enumerating all available controllers and then ask each to
find its audio channels, we change the initialization sequence to match
what happens in the Networking subsystem and Graphics subsystem - we
essentially probe for a matching driver on a PCI device, create a device
instance, and immediately initialize it.
This in fact allows us to immediately find any hardware initialization
issues and report it, and then dropping the created instance, as usually
being done in other initialization paths in the Kernel.
This also opens the opportunity to propagate errors when failed to
initialize an AudioChannel instance, and it will be addressed in a
future commit.
This is an implementation that tries to follow the spec as closely as
possible, and works with Qemu's Intel HDA and some bare metal HDA
controllers out there. Compiling with `INTEL_HDA_DEBUG=on` will provide
a lot of detailed information that could help us getting this to work
on more bare metal controllers as well :^)
Output format is limited to `i16` samples for now.
