global: remove unnecessary includes from headers.

Each header should only include the other headers it needs to compile;
`devtools/reduce-includes.sh */*.h` does this.  The C files then need
additional includes if they don't compile.

And remove the entirely useless wire/onion_wire.h, which only serves to include wire/onion_wiregen.h.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

connectd/connectd_wire.csv

@@ -1,10 +1,8 @@
-#include <bitcoin/block.h>
 #include <common/channel_id.h>
-#include <common/cryptomsg.h>
 #include <common/features.h>
 #include <common/node_id.h>
 #include <common/wireaddr.h>
-#include <wire/onion_wire.h>
+#include <wire/onion_wiregen.h>
 
 msgtype,connectd_init,2000
 msgdata,connectd_init,chainparams,chainparams,