client: fix config object issue

[ScottyPoi]

This fixes an issue where discv5 was not being instantiated with configuration options set during PortalNetwork.create.

We define a defaultConfig object for PortalNetwork.create, and modify it using args passed to the function like this:

const config = { ...defaultConfig, ...opts.config }

However, this was not effectively combining configuration options set specifically for discv5 which were in nested object config.config.

To fix this, we add this line after the one above:

config.config = { ...defaultConfig.config, ...opts.config.config }

This solves the issue, and now discv5 starts with the expected configuration.

[acolytec3]

LGTM

[acolytec3]

Added one additional opt update where the shouldRefresh opt wasn't being populated in the create function.