BREAKING CHANGE(misconf): Removing support for less commonly used Rego features

[simar7]

Motivation

We will be deprecating some of the Rego features that Trivy currently supports as we believe they are less likely to be used now as there exist better and more commonly used alternatives as described below:

Removing support for warn and violation check types

Currently Trivy supports deny, warn and violation types. This was previously added when Trivy misconfiguration scanning didn't fully support severities and had to rely on Rego checks themselves to determine the level of the check. With the Rego checks supporting severities just as any other scan type does, there's no need for using these check types.

Removing combined option for check evaluation

Currently Trivy supports the ability for multiple Rego inputs to be combined into one. This feature has limited uses and requires custom checks to be written in a certain way that currently does not fit with the Trivy scanning model.

Timeline

These features will be deprecated starting in Trivy v0.58