Rudimentary unit tests for Validation and Defaults behavior on Policy config

[tanveergill]

Why

• This test detects whether Validation or Defaults are completely broken

What

• Write tests here: https://github.com/fluxninja/aperture/blob/main/pkg/policies/controlplane/validator_test.go
• Start with a super policy with all the pieces required for following unit tests.
• The super policy should not generate an error when passed through policyValidator.ValidateObject
• Modify the super policy for each unit test

Defaults Tests

• Check that PromQL.evaludation_interval defaults to 10s when unset

Validation Tests

• Remove ConcurrencyLimiter.selector and check that error occurs
• Set WorkloadParameters.priority as 2000 and check that error occurs