[IMPL] - Custom backend server and improved configuration capabilities

[KronosDev-Pro]

Original PR: #4337

Idea

Customize the backend server configuration as you like, and create a complete new backend server support.

can be easily split into another reflex package, for example pip install reflex[granian].

Example

We can define which BackendServer to use for development and production modes and thus customize the configuration (all parameters for each BackendServer are the actual parameters corresponding to the web server involved).

import reflex as rx
from reflex import server

config = rx.Config(
    app_name="examples",
    backend_server_dev = server.GunicornBackendServer(
        worker_class="uvicorn.workers.UvicornH11Worker",
        max_requests=100,
        max_requests_jitter=25,
        timeout=120,
        threads=1,
        workers=1,
    ),
    backend_server_prod = server.GranianBackendServer(
        threads=2,
        workers=4,
    )
)

We can also create a customized BackendServer with the CustomBackendServer class, such as GranianBackendServer

---

All Submissions:

• Have you followed the guidelines stated in CONTRIBUTING.md file?
• Have you checked to ensure there aren't any other open Pull Requests for the desired changed?

Type of change

• New feature (non-breaking change which adds functionality)
• This change requires a documentation update

New Feature Submission:

• Does your submission pass the tests?
• Have you linted your code locally prior to submission?

Changes To Core Features:

• Have you added an explanation of what your changes do and why you'd like us to include them?
• Have you written new tests for your core changes, as applicable?
• Have you successfully ran tests with your changes locally?

[KronosDev-Pro]

@adhami3310 this is the new PR, apparently it solved the problems

I will test again, with a different version of python and other sample projects. ✔️

[adhami3310]

hi @KronosDev-Pro ! since then, we have turned into a different approach, instead of adding a custom backend server, we ended up implementing it such that app itself can be called with an asgi server, as such there's no need for adding that to the config

nonetheless, we appreciate your work here! :) let me know if there are things you're interested in contributing otherwise