[Proof of Concept] Make Semian work with activerecord-trilogy-adapter

[adrianna-chang-shopify]

An alternative approach to #420, where we target resource acquisition at the Active Record adapter layer instead of patching the Trilogy client directly.

This is a simpler approach, and allows us to deal with native Active Record errors instead of the various errors Trilogy is currently raising. The tests are also a lot simpler because we don't have to handle re-instantiating the Trilogy client every time the connection is closed (either server or client side).

Caveats:

• We'll need to deal with SFR separately
• There is still work to be done in activerecord-trilogy-adapter to make some of the error classes better (specifically in #new_client)

[adrianna-chang-shopify]

Okay, so unfortunately making half_open_resource_timeout work is still a bit hacky, even working at the adapter layer. I'm racking my brain for another way to do this, but not sure we have many options.

Basically, the Trilogy adapter forwards configs to the client, one of which is the read_timeout. In the context of with_resource_timeout, we might be connecting to the db, in which case connection is nil. Consequently, the only way I see being able to set a new (temp) read_timeout is to mutate the @config so that the newly instantiated client gets created with the timeout we want. If we have the connection already, we can reach directly to the connection (the Trilogy::Client) and modify the read_timeout.

In the ensure block, we can reset the timeout on the connection, and I'm assuming we should also reset the config.

This is additionally complex because if no read_timeout is set in the config, we need to use the client's default, which I know is 0 but could potentially change.

[adrianna-chang-shopify]

Superseded by #468