implement wait-for-model/tool helper

[keighrim]

Because

Because some wrapper CLAMS apps use fairly large models that take a few minutes to fully load in the memory, if an app user sends POST requests during that initiation time of underlying models/tools, the app would most likely behave badly. This already has happened in clamsproject/app-dbpedia-spotlight-wrapper#3, and we'd like to make a SDK-level helper function to make sure apps don't "die" in such synchronous/asynchronous model initiation scenarios.

Done when

SDK has an implementation of

1. external server timeout checker
2. internal (in-memory) model readiness check
3. and more...?

Additional context

This will be more of a problem soon, as vision-related apps are moving toward ViT-based models.