Consolidate Vm implementations

As much as the two vm implementations SEEM different, the differences
largely lie in how we're getting the nbd proxy socket.  One is relying
on launching a process (nbd-proxy), the other is getting the fd from
dbus.  Given [1] exists and is in process, we need to have a plan for
getting these two VM implementations into one, once that patchset is
complete.

This commit: Splits the vm-websocket option into vm-websocket-provider,
providing two options, nbd-proxy, and virtual-media (the names of the
respective apps).  To accomplish this, it moves the contents of
nbd-proxy into include/vm-websocket, so we can compare the similarities
and start consolidating.

The longer term intent is that the nbd-proxy option will be completely
removed, and the code deleted.  This has the additional advantage that
we will no longer require the boost::process dependency, as all info
will be available on dbus.

As part of this, the nbd proxy websocket is also registered at /vm/0/0,
to be backward compatible with the old interfaces.

Tested: Code compiles.  Need some help here.

[1] https://gerrit.openbmc.org/c/openbmc/jsnbd/+/49944

Change-Id: Iedbca169ea40d45a8775f843792b874a248bb594
Signed-off-by: Ed Tanous <ed@tanous.net>
diff --git a/config/meson.build b/config/meson.build
index 26c9bd4..9533bd6 100644
--- a/config/meson.build
+++ b/config/meson.build
@@ -26,6 +26,9 @@
     get_option('mutual-tls-common-name-parsing') == 'meta',
 )
 
+conf_data.set10('BMCWEB_VIRTUAL_MEDIA_VM', get_option('vm-websocket').allowed())
+conf_data.set10('BMCWEB_VIRTUAL_MEDIA_NBD', false)
+
 # Logging level
 loglvlopt = get_option('bmcweb-logging')
 if get_option('buildtype').startswith('debug') and loglvlopt == 'disabled'