Number of configurations for successes

[jpreese]

Most of the diff is from formatting, and simplifying a couple of the tests. The most notable changes include:

• Bump OPA from 0.20.5 to 0.23.2
• Convert successes property in JSON output to a count of successes.
• Use the number of configurations as part of the success count calculation.

Further explanation:

Currently, we're counting the number of rules that match the rule regex (e.g. deny), and we use that value to calculate the number of successes after all evaluations have completed:

	for i := len(totalErrors) + len(totalSuccesses) + len(totalExceptions); i < numberOfRules; i++ {
		totalSuccesses = append(totalSuccesses, output.Result{})
	}

(https://github.com/open-policy-agent/conftest/blob/master/internal/runner/test.go#L267)

However, when multiple configurations are involved, such is the case with multi-document yamls, json, etc--the number of tests is actually the number of rules multipled by how many configurations we are testing against:

	// When there are multiple configurations to be tested, we multiply the number of rules
	// by how many configurations will be tested to get the total number of tests.
	totalTests := numberOfRules
	if _, ok := input.([]interface{}); ok {
		totalTests = numberOfRules * len(input.([]interface{}))
	}

Resolves:
#309
#370

[Blokje5]

LGTM! Good cleanups as well!