Add a method to retrieve the full Chain object in a read-only chain management system

[sinolopes]

In applications using the wagmi framework, it's currently possible to perform basic chain management in read-only mode using switchChain to change the active chain and useChainId to retrieve the current chain ID. However, there is no native method to retrieve the full details of a chain, such as its name or symbol, without relying on external mappings or additional custom logic.

Current Problem:
To display useful information about the active chain, such as its name or symbol, developers need to maintain a local list of supported chains or implement additional logic. This adds unnecessary complexity and reduces the simplicity of using wagmi.

Proposed Solution:
Introduce a new feature to directly retrieve the full Chain object for the active chain. This could be implemented as a hook or a method, extending the functionality of useChainId or switchChain. For example:

1. New Hook or Method:

const { chain } = useChain();
console.log(chain.name, chain.symbol); // Ethereum, ETH

2. Enhancement of Existing useChainId:
   Allow useChainId to return both the ID and the full Chain object.

3. Integration with useSwitchChain:
   Extend the functionality to add current Chain