feat: allow null, undefined, booleans, string and numbers as jsx elements

[ncpa0cpl]

It is now possible to return other things from function components than elements created via createElement or JSX syntax. Anything that is not an object, string or number will be treated as if <></> was returned, returned strings and numbers will be treated as <>{value}</>, objects are expected to be elements created via createElement or JSX syntax (no change here).

This means that the following components are now possible:

function MyComponent() {
  return !!condition && <div>...</div>;
} 

function MyComponent() {
  return "Hello";
} 

function MyComponent() {
  return 2023;
} 

// ok
renderToHtml(
  <div>
    <MyComponent />
  </div>
)