[FR] Add support for multiple nodes

[phroi]

Hello CKB DevRel folks!!
I was wondering, have you considered adding support for multiple nodes to use as RPC providers?

This could work in two ways, both as load balancing and/or as a fallback. The issue that just happened is that a famous RPC provider fully blocked requests from the iCKB integration in nervdao.com, making the DApp unusable for users. More generally the main issue that we'd like to avoid is that DApps go down because a single RPC provider is experiencing an issue. Providing support for multiple RPC providers would make DApps built on top of CCC more reliable.

Keep up the Great Work,
Phroi