Make TJWS.CheckCompactToken more strict

[havrlisan]

Hi. I noticed your code in TJWS.CheckCompactToken is rather simple, where you check if the given string contains 3 non-empty parts separated by a dot. While this might be sufficient for most cases, it could be more strict in a way that you try to parse the Header and Claims (Payload) section to a JSON value. For example:

class function TJWS.CheckCompactToken(const Value: TJOSEBytes; const AStrict: Boolean): Boolean;
var
  LRes: TStringDynArray;
  LIndex: Integer;
begin
  Result := True;

  if Value.IsEmpty then
    Exit(False);

  LRes := SplitString(Value, PART_SEPARATOR);
  if not (Length(LRes) = COMPACT_PARTS) then
    Exit(False);

  for LIndex := 0 to Length(LRes) - 1 do
  begin
    if LRes[LIndex].IsEmpty then
      Exit(False);
  end;
  
  if TJSONObject.ParseJSONValue(LRes[0]) = nil then
    Exit(False);
  if TJSONObject.ParseJSONValue(LRes[1]) = nil then
    Exit(False);
end;

Thanks for creating this library and writing such clean and readable code!

[paolo-rossi]

Hello @havrlisan

Yes, I knew that the check was not "strong" but I simply forgot to refactor this function, I like your solution... how about you create a PR so I can credit you for this work?

Paolo.