feat: JsonRpcClient, default to Unauthenticated state

[miraclx]

Default the JsonRpcClient's authentication state to being Unauthenticated, much like HashMap's RandomState. Makes it so you don't have to worry about authentication until you actually need to. So the auth module shouldn't be imported without you doing any authentication.

Diff

-use near_jsonrpc_client::{auth, JsonRpcClient};
+use near_jsonrpc_client::JsonRpcClient;

struct App {
-    client: JsonRpcClient<auth::Unauthenticated>, // <-- pain
+    client: JsonRpcClient,
}

enum Network {
    MainNet,
    TestNet,
}

- fn mk_client(network: Network) -> JsonRpcClient<auth::Unauthenticated> { // <-- pain
+ fn mk_client(network: Network) -> JsonRpcClient {
    let rpc_url = match network {
        Network::MainNet => "https://rpc.mainnet.near.org",
        Network::TestNet => "https://rpc.testnet.near.org",
    };
    JsonRpcClient::connect(rpc_url)
}