endpoint providers and fallbacks

The default should be easy, so a junior dev can simple provide an URL and get up and running. However, an array of fallback endpoints could be provided if exists!

```ts
interface EndpointWeight {
url: string;
weight: number;
}

export const getRpc = async (endpoints: EndpointWeight[]) => {
//...
};
```

## example docs:

- [ ] https://docs.ethers.io/v5/api/providers/provider/
- [ ] https://docs.ethers.io/v5/api/providers/other/#FallbackProvider

## example providers that are services

- https://blog.cosmos.network/kyve-the-web3-data-lake-solution-turns-to-cosmos-to-launch-scalable-and-streamlined-layer-1-16a2f4794f86
- https://www.pokt.network/