Add Alchemy endpoint for Arbitrum Sepolia (#3665)

### What

As Alchemy started to support Arbitrum Sepolia we can switch the wallet
to use Alchemy endpoint by default.

Issues:
- ethers providers doesn't know about Arbitrum Sepolia network,
workaround was added (same as for eth sepolia network)
- seems like there is a problem with using `external` flag for
`alchemy_getAssetTransfers` on Arb Sepolia, it is responding with server
error that these are not supported on a given chain [despite docs
claiming
otherwise](https://docs.alchemy.com/reference/alchemy-getassettransfers)
- `alchemy_getTokenBalances` is failing often with server error
(timeout) - seems like it is a problem on Alchemy side

These are not totally blocking because most of the time requests are
working fine and we have backup providers as well but I would rather
talk to Alchemy support about these problems first, before merging this
PR.

### Testing steps

- [ ] reinstall extension/reload background script
- [ ] open the background console
- [ ] add some accounts, use Arbitrum sepolia network
- [ ] make sure requests are going through the Alchemy's Arbitrum
Sepolia endpoint

Latest build:
[extension-builds-3665](https://github.com/tahowallet/extension/suites/18347933259/artifacts/1061913309)
(as of Mon, 20 Nov 2023 16:33:19 GMT).

background/constants/networks.ts

@@ -197,10 +197,15 @@ export const NETWORKS_SUPPORTING_SWAPS = new Set(
 )
 
 export const ALCHEMY_SUPPORTED_CHAIN_IDS = new Set(
-  // TODO: Add `ARBITRUM_SEPOLIA` once Alchemy creates a dedicated  RPC.
-  [ETHEREUM, POLYGON, ARBITRUM_ONE, OPTIMISM, GOERLI, SEPOLIA].map(
-    (network) => network.chainID,
-  ),
+  [
+    ETHEREUM,
+    POLYGON,
+    ARBITRUM_ONE,
+    OPTIMISM,
+    GOERLI,
+    SEPOLIA,
+    ARBITRUM_SEPOLIA,
+  ].map((network) => network.chainID),
 )
 
 export const FLASHBOTS_SUPPORTED_CHAIN_IDS = new Set([ETHEREUM.chainID])

background/services/chain/taho-provider.ts

@@ -20,10 +20,13 @@ import { ConnectionInfo } from "@ethersproject/web"
 export default class TahoAlchemyProvider extends AlchemyProvider {
   static override getUrl(network: Network, apiKey: string): ConnectionInfo {
     let host = null
-    switch (network.name) {
-      case "sepolia":
+    switch (network.chainId) {
+      case 11155111: // Ethereum Sepolia
         host = "eth-sepolia.g.alchemy.com/v2/"
         break
+      case 421614: // Arbitrum Sepolia
+        host = "arb-sepolia.g.alchemy.com/v2/"
+        break
       default:
         return AlchemyProvider.getUrl(network, apiKey)
     }