add option to disable Tailwind

[ElijahAhianyo]

This PR provides an option to disable the out-of-the-box supported Tailwind. To do that, simply set the tailwind config to None :

rxconfig.py

import reflex as rx

config = ExampleConfig(
    app_name="example",
    tailwind= None
)

fixes #1829

Docs: reflex-dev/reflex-web#205

[Lendemor]

Shouldn't tailwind=None be enough to disable tailwind rather than add a disable field?

Also I was thinking we should remove the base tailwind from package.json and only install it if tailwind is not None.

[Lendemor]

Nice!