refactor: merge osd into machined

This merges `osd` API into `machined`. API was copied from `osd` into
`machined`, and `osd` API was deprecated.

For backwards compatibility, `machined` still implements `osd` API, so
older Talos API clients can still talk to the node without changes.

Docs were updated. No functional changes.

Signed-off-by: Andrey Smirnov <smirnov.andrey@gmail.com>

internal/app/apid/main.go

@@ -72,6 +72,7 @@ func main() {
 	// all existing streaming methods
 	for _, methodName := range []string{
 		"/machine.MachineService/Copy",
+		"/machine.MachineService/Dmesg",
 		"/machine.MachineService/Events",
 		"/machine.MachineService/Kubeconfig",
 		"/machine.MachineService/List",