Resolves #257

[muditchaudhary]

Resolves #257

Description of changes:

1. Creates public getter methods for AuthorizationError
2. Overrides .toString() for AuthorizationError, DetailedError, and SourceLabel.

Example:

Set<String> reasons = new HashSet<>();
reasons.add("p1");

List<SourceLabel> sourceLabel = List.of(new SourceLabel(Optional.of("sourceLabel"), 0, 10));

final Diagnostics diagnostics = new Diagnostics(new HashSet<>(reasons),
        List.of(new AuthorizationError("policyError1",
                new DetailedError("message", Optional.of("dummyHelp"), 
                Optional.of("dummyCode"),
                Optional.of("dummyUrl"), 
                Optional.of(Severity.Error), 
                Optional.of(sourceLabel),
                Optional.empty()))));

final AuthorizationSuccessResponse authorizationSuccessResponse = new AuthorizationSuccessResponse(
        Decision.Deny, diagnostics);
        
System.out.println(authorizationSuccessResponse)

Output

Deny, reason [p1], 
errors [AuthorizationError{policyId=policyError1, error=DetailedError{message="message", help="dummyHelp", code="dummyCode", url="dummyUrl", severity=Error, sourcelocations=[SourceLabel{label="sourceLabel", start=0, end=10}], related=[]}}