Refactor AWS resource calls into classes

[ajvb]

from this discussion: https://github.com/mozilla/frost/pull/417#discussion_r524492537

Currently, there is some brittleness around how our AWS resource calls and the id extraction are separated from each other.

This is currently leading to vague and brittle get_resource_id() functions that parameterize uses to get the test id.

Along side this, there are what amount to hacks for dealing with "resources" that are lists or do not exist (i.e. https://github.com/mozilla/frost/pull/417/files#diff-ee242f021608b58d502ee9c4c6273c6145f18e6703f8329b3799c50db5c8fe95R155)

As a result, it seems like it may make sense to transform the resources.py functions into classes (dataclasses, boto3 classes, etc).