In some countries, Solana RPC endpoints are blocked.

"https://api.mainnet-beta.solana.com" and "https://api.devnet.solana.com/" are both blocked in China.

When I'm trying to connect, I'm getting this error:
```
 https://api.devnet.solana.com/ failed, reason: connect ETIMEDOUT 103.240.182.55:443
```

How to get @solana/web3.js to access the RPC endpoints through a proxy?