feat: expose current ceramic network via api

[dav1do]

This adds a new endpoint to support retrieving the current network the server is connected to. I changing the name formatting to remove /ceramic/ and return the values that match more closely to what we previously used in js-ceramic. It is possibly a subtly breaking change if people were relying on this string representation to match the pubsub topics, but I can't find any uses in the repo, http client or keramik so went ahead and changed it. Open to implementing Display or another function instead if others deem that worthwhile.

I also added inmemory as an alias of in-memory for the network cli flag so either can be passed in. It's not advertised in help/completion but it will work if passed in.

# GET /ceramic/network
❯ curl http://127.0.0.1:5101/ceramic/config/network
{"name":"local-0"}

[linear]

AES-209 Error if js-ceramic and C1 mismatch on what network they are using

[stbrody]

LGTM mod question about namespacing the endpoint