[easylog][fix]fix path when roll files

[qicosmos]

Why

Close #495

when log dir is not exist, create the dir;

append path when roll files;

What is changing

Example

TEST_CASE("test roll files and automatic create directories") {
  std::string filename = "a/b/c/test.txt";
  std::filesystem::remove(filename);
  CHECK(!std::filesystem::exists(filename));
  constexpr size_t InstanceId = 888;
  easylog::init_log<InstanceId>(Severity::DEBUG, filename, false, true, 20, 3,
                                true);
  CHECK(std::filesystem::exists(filename));
  MELOG_INFO(InstanceId) << 42 << " " << 4.5 << 'a' << " it is a test";
  MELOG_INFO(InstanceId) << 42 << " " << 4.5 << 'a' << " it is a test";
  MELOG_INFO(InstanceId) << 42 << " " << 4.5 << 'a' << " it is a test";

  CHECK(std::filesystem::exists(filename));
  CHECK(std::filesystem::exists("a/b/c/test.1.txt"));
  CHECK(std::filesystem::exists("a/b/c/test.2.txt"));

  std::error_code ec;
  std::filesystem::remove_all("a", ec);
  std::cout << ec.message() << "\n";
}