Support custom annotations

[drewhamilton]

Consumers should be able to specify their own annotation class to use instead of dev.drewhamilton.extracare.DataApi if they want. Redacted allows this.

I initially left this out because I envisioned the @DataApi annotation eventually needing parameters, like generateBuilder = true etc. But I think it will make more sense to add features like that either as separate annotations or a separate plugin, because annotations with parameters get clunky if they have to be used throughout a whole code base. Thus, it should be safe to allow consumers to provide any annotation they choose.