[REQ][RUBY] Use `Faraday`'s Persistent HTTP Adapter

Is your feature request related to a problem?

When using standard Faraday, the default adapter is net-http. This uses Ruby's stdlib Net::HTTP / Faraday's Net::HTTP adapter to create a new TCP socket and close it upon every request.

Doing this every time for clients that make a high # of requests tend to add an extra latency span, since we are:

1. Not re-using the TCP Socket.
2. Creating and closing a TCP Socket for each request.
3. Going through the TCP Network Protocol.

If you take a look here it calls http#start, then within the Ruby block, it calls opened_http#request.

Looking in Net::HTTP here the #start call ends up opening a new TCP Socket connection with the server.

Then we initiate the request again in Faraday, making two network hops each time.

Describe the solution you'd like

I believe there are a few things that would be needed. We would need to memoize the api client's connection instance. And we would also need to add Faraday's persistent adapter.

I believe using Faraday's net http persistent adapter alleviates this concern as it re-uses the TCP socket and keeps it open for subsequent client requests.

Describe alternatives you've considered

We've tried re-writing our own mustache templates to generate this, but it feels a bit hacky to constantly overwrite the upstream's templates. I haven't spent too much time digging into how the mustache templates work in this library yet - so unfortunately I'm not too familiar where to begin looking 😢

Start by reviewing the Ruby Mustache templates in the generator, then compare Faraday's net_http adapter at lib/faraday/adapter/net_http.rb with Ruby Net::HTTP at lib/net/http.rb. Trace how generated clients create connections and determine how the persistent adapter and connection reuse should be integrated; done means repeated requests reuse an open connection without breaking generated clients.