Use v3 logging (and hide verbose log messages when verbose switch not used)

[NoxHarmonium]

I found out that Serverless actually document how the plugin logging works somewhere:

https://github.com/serverless/serverless/blob/8460b25a516a001710efe9c1fdf23604d3b2e656/docs/guides/plugins/cli-output.md

We seem to be using the deprecated v2 logging (which I reverse engineered from the serverless-webpack plugin) but we should probably use the v3 version. This would also allow us to use log levels to hide noisy log messages.

At the noisiest level (Debug) we could even log patches to show how was-durable-lambda is patching the serverless config.