Feat/reward multiwallet

[purusang]

This pr enable two important features:

• allows multiple wallet management with custom_signet as obligatory and first one.
  The no of wallets is controlled by NUM_WALLETS env, if its 0 then node will only have custom_signet wallet.
• enables pre-mining max 100 blocks to an address derived from custom_signet.

[sapinb]

@Rajil1213 Are we planning to connect all the bridge nodes to the same bitcoin node, which is also the miner node of the signet? I dont think this is a good idea.

[Rajil1213]

Are we planning to connect all the bridge nodes to the same bitcoin node, which is also the miner node of the signet? I dont think this is a good idea.

@sapinb that's not a requirement. Each bridge node needs two wallets:

1. To make front-payments, fund dust outputs and for CPFP-ing transactions. This requires a non-deterministic amount of funds so it should be well-funded at all times.
2. To stake some funds. This only requires 1 BTC (assuming that that's the deposit denomination).

We are planning to deploy 3 bridge nodes. So that means we need 3 well-funded addresses and 3 addresses with 1 BTC. These addresses will be derived from some master xpriv during bridge deployment.

[purusang]

@Rajil1213 Got it. So can I modify the program such that it takes some addresses (bridge nodes) and mining rewards are sent to them in cycle instead of managing arbritrary wallets for them?

[Rajil1213]

So can I modify the program such that it takes some addresses (bridge nodes) and mining rewards are sent to them in cycle instead of managing arbritrary wallets for them?

Yes. That's the most straightforward approach. These wallets don't need a lot of funds either. One wallet only ever needs 1 BTC. The other wallet needs a constant influx of funds but even with just 4 BTC, it can serve ~10000 deposits/withdrawals (not considering the transaction fees).

Another thing to note is that for the first deployment we also require the miner node to be run with the following options:

minrelaytxfee=0.0
blockmintxfee=0.0
dustRelayFee=0.0

This will allow transactions with 0 fees to be mined as well since we are not handling any dynamic fees during our first deployment of the bridge.