Empty token is not handled in RPC client

[eshaan7]

This line doesn't properly handle the case of empty token that is useful if node is running with skip-auth flag enabled.

celestia-node/api/rpc/client/client.go

Line 69 in 5f48673

authHeader := http.Header{perms.AuthKey: []string{fmt.Sprintf("Bearer %s", token)}}

This should be handled similar to the logic in celestia-openrpc:

https://github.com/celestiaorg/celestia-openrpc/blob/089b92870cb65f8e190ad6d7215b645b942e43b6/client.go#L44-L47