fix: HRC20 burn/burnFrom BNish type and BridgeToken devnet multisig signer

[D2758695161]

Description

Fixed two bugs in the Harmony Marketplace SDK:

Bug 1: HRC20 burn/burnFrom parameter type mismatch

The burn() and burnFrom() methods in HRC20 class had their amount parameter typed as number, but the HRC20 standard and the SDK README documentation specify that amounts should accept BNish type (BN | Arrayish | bigint | number).

Before:

public burn(amount: number, txOptions?: ITransactionOptions) {
  return this.send("burn", [amount], txOptions)
}
public burnFrom(account: string, amount: number, txOptions?: ITransactionOptions) {
  return this.send("burnFrom", [account, amount], txOptions)
}

After:

public burn(amount: BNish, txOptions?: ITransactionOptions): Promise<Transaction> {
  return this.send("burn", [amount], txOptions)
}
public burnFrom(account: string, amount: BNish, txOptions?: ITransactionOptions): Promise<Transaction> {
  return this.send("burnFrom", [account, amount], txOptions)
}

Also added missing Promise return type annotations.

Bug 2: BridgeToken devnet multisig signer always uses mainnet address

In the BridgeToken constructor, hmyMasterWallet.setSigner() was always called with MAINNET_MULTISIG_WALLET regardless of whether the network was mainnet or devnet.

Before:

this.hmyMasterWallet.setSigner(MAINNET_MULTISIG_WALLET)

After:

this.hmyMasterWallet = this.hmyMasterWallet.setSigner(
  this.isMainnet ? MAINNET_MULTISIG_WALLET : DEVNET_MULTISIG_WALLET,
)

---

Bounty claim: This PR addresses the coding errors bug bounty for Harmony Marketplace SDK (harmony-one/bounties#125).

Payment address for bounty: 0xaae0101ac77a2e4e0ea826eb4d309374f029b0a6

[D2758695161]

👋 Just checking in on this PR. Happy to make any adjustments if needed. Ready for merge whenever you are!

[D2758695161]

👋 Hi! Just bumping this PR. All ready for merge - let me know if you need any changes! 🦞

[D2758695161]

Hi @owner, my PR #78 (HRC20 fix) is still open and ready for review. Could you please take a look? Bounty payment address: 0xaae0101ac77a2e4e0ea826eb4d309374f029b0a6 (ERC20/BSC/ETH). Thank you!

[D2758695161]

Gentle bump - PR ready to merge. Bounty: TBD USDT ? �xaae0101ac77a2e4e0ea826eb4d309374f029b0a6. Please review.

[D2758695161]

?? Bump - this PR is ready to merge. Please let me know if you need any changes or have questions. Happy to iterate!

[D2758695161]

@blockcoders — PR #78 fixes HRC20 burn/burnFrom BNish type and BridgeToken devnet signer. Ready to merge.