Merkle proof input signals can be reduced in size

[Stentonian]

e.g.

zk-proof-of-assets/tests/2_sigs/layer_two_input.json

Lines 394 to 420 in 3092dda

	"path_indices": [
	[
	0,
	1,
	1,
	0,
	0,
	1,
	1,
	1,
	1,
	1,
	0,
	1,
	1,
	0,
	1,
	1,
	1,
	1,
	1,
	1,
	1,
	1,
	1,
	1
	],

Only 1 bit is needed for each element but a whole field element is used. We can squash the array to a single binary value.