feat: use RLN with RC instead of Poseidon

[rymnc]

With the implementation of the RC hash in circom, we can substitute it instead of Poseidon in the calculation of -
a. identityCommitment
b. rateCommitment
c. a1
d. levelHashes in the MerkleInclusionProof

Here's the diff of constraints for both the RLN and withdraw circuits

1. RLN Circuit =>

circom compiler 2.1.5
-template instances: 216
+template instances: 48
-non-linear constraints: 5820
+non-linear constraints: 957
linear constraints: 0
public inputs: 2
public outputs: 3
private inputs: 43
private outputs: 0
-wires: 5844
+wires: 1053
-labels: 18553
+labels: 24733

2. Withdraw Circuit =>

circom compiler 2.1.5
-template instances: 71
+template instances: 42
-non-linear constraints: 214
+non-linear constraints: 37
linear constraints: 0
public inputs: 1
public outputs: 1
private inputs: 1
private outputs: 0
-wires: 217
+wires: 43
-labels: 585
+labels: 1021

[rymnc]

Tests fail since there is no RC implementation in js - I can add a known answer test if you'd like :)