CAIP-2 chain IDs should be defined as constants

[gibson042]

(originally posted by @gibson042 in #12396 (comment))

This pattern [an object keyed by CAIP-2 chain IDs] keeps coming up, and I like the ability to associate specific links with the data but not the repetition of magic strings. I think a future PR should refactor, e.g.

import {
  CaipChainIds as CHAIN_IDS_BY_CLUSTER,
} from '@agoric/portfolio-api/src/constants.js';

const { entries, fromEntries, values } = Object;

/** XXX this probably belongs in @agoric/orchestration */
const CHAIN_IDS: Record<string, CaipChainId> = {
  // mainnet
  ARBITRUM: 'eip155:42161',
  AVALANCHE: 'eip155:43114',
  BASE: 'eip155:8453',
  ETHEREUM: 'eip155:1',
  OPTIMISM: 'eip155:10',
  AGORIC: 'cosmos:agoric-3',
  NOBLE: 'cosmos:noble-1',
  // testnet
  ARBITRUM_SEPOLIA: 'eip155:421614',
  AVALANCHE_FUJI: 'eip155:43113',
  BASE_SEPOLIA: 'eip155:84532',
  ETHEREUM_SEPOLIA: 'eip155:11155111',
  OPTIMISM_SEPOLIA: 'eip155:11155420',
  AGORIC_DEVNET: 'cosmos:agoricdev-25',
  NOBLE_TESTNET: 'cosmos:grand-1',
};
{
  // Cross-check
  const allChainIds = new Set(
    values(CHAIN_IDS_BY_CLUSTER).flatMap(cluster => values(cluster)),
  );
  const unknownChains = entries(CHAIN_IDS).filter(
    ([_name, chainId]) => !allChainIds.has(chainId),
  );
  if (unknownChains.length) {
    throw Error(
      `unknown CAIP-2 chain ids: ${JSON.stringify(fromEntries(unknownChains))}`,
    );
  }
}
…
const traceFilterSupportedChains: ReadonlySet<CaipChainId> = new Set([
  // mainnet
  CHAIN_IDS.BASE,
  CHAIN_IDS.ETHEREUM,
  CHAIN_IDS.OPTIMISM,
  // testnet
  CHAIN_IDS.BASE_SEPOLIA,
  CHAIN_IDS.ETHEREUM_SEPOLIA,
  CHAIN_IDS.OPTIMISM_SEPOLIA
]);

(and likewise for similar constants)