feat: add estimateMultihopFee function

[npty]

Description

https://axelarnetwork.atlassian.net/browse/AXE-6367

This PR adds a function estimateMultihopFee to estimate gas fee for multiple-hops route.

Please note: The devnet amplifier configuration URL is temporarily set to https://melted-fayth-nptytn-57e5d396.koyeb.app/chain/devnet-amplifier. This will be updated once the official URL becomes available.

Implementation

The function is a wrapper for a call to the endpoint /gmp/estimateGasFeeForNHops in axelarscan api. It validates given source chains and destination chains before making the api call.

Usage

The estimateMultihopFee method provides flexible gas fee estimation for complex multi-hop transfers. This is particularly useful for:

• Two-way transfers
• ITS Hub
• Complex cross-chain interactions

const api = new AxelarQueryAPI({
  environment: Environment.DEVNET,
});

// ITS Hub
const fee = await api.estimateMultihopFee([
  {
    sourceChain: "avalanche-fuji",
    destinationChain: "axelarnet",
    gasLimit: "700000",
  },
  {
    sourceChain: "axelarnet",
    destinationChain: "sui-test2",
    gasLimit: "700000",
  }
]);

// Two-way transfer with detailed fees
const twoWayFee = await api.estimateMultihopFee([
  // First transfer: Chain A -> Chain B
  {
    sourceChain: "ethereum",
    destinationChain: "avalanche",
    gasLimit: "700000",
    sourceTokenSymbol: "axlUSDC",
  },
  // Return transfer: Chain B -> Chain A
  {
    sourceChain: "avalanche",
    destinationChain: "ethereum",
    gasLimit: "500000",
    sourceTokenSymbol: "axlUSDC",
  }
], {
  showDetailedFees: true
});

// Complex multi-hop with express and custom parameters
const complexFee = await api.estimateMultihopFee([
  // First hop with express eligibility check
  {
    sourceChain: "ethereum",
    destinationChain: "polygon",
    gasLimit: "700000",
    sourceTokenSymbol: "USDC",
    sourceTokenAddress: "0xSource1...",
    sourceContractAddress: "0xContract1...",
    gasMultiplier: 1.1
  },
  // Intermediate hop
  {
    sourceChain: "polygon",
    destinationChain: "avalanche",
    gasLimit: "500000",
    minGasPrice: "1000000000",
    symbol: "axlUSDC"
  },
  // Final hop with contract execution
  {
    sourceChain: "avalanche",
    destinationChain: "fantom",
    gasLimit: "800000",
    executeData: "0x...",
    destinationContractAddress: "0xDest3...",
    amountInUnits: "1000000"
  }
]);

Blockers For Merging

• Needdevnet-amplifier config with latest sui contract info (same as this one) deployed to s3. I've hardcoded it to point to the raw file in the github repo instead.

[canhtrinh]

Looks good! as a follow up @npty, we should build this into the main estimateGasFee function as well