Improve how we handle wallet_addEthereumChain with same chainID but different rpc urls

[bschorchit]

Context: https://github.com/MetaMask/metamask-extension/issues/15840

We should better communicate to users that the dapp is proposing to add a network they already have, but with a different rpc url and give users the choice to switch to the network they already have or adding it as a new custom network with the new rpc url - or maybe even replacing the current rpc url. This ticket needs more definition and design before it's ready for development.

[helpfulBro]

Can we please also consider an option (maybe advanced settings) to ignore prompts to add RPCs for networks where one is already defined.

For example, if I am using a private RPC I'm not interested in adding another RPC for the same network.

Actually most times adding a new RPC where one already exists is probably not helpful and could be used to spam or inject malicious RPCs for unknowing users.

Thanks 🙏

[bschorchit]

The copy mentioned here https://github.com/MetaMask/metamask-extension/issues/16712 should be considered/applied for this issue as well.