Allow choosing the CP version in web installer

[0wwafa]

Web installer is nice but only updates to a fixed (latest) binary.
Please add a button to select a local binary.

[Neradoc]

Hi, I believe you are talking about the installer on circuitpython.org
Here is a web version of esptool to install binaries, and a guide:
https://adafruit.github.io/Adafruit_WebSerial_ESPTool/
https://learn.adafruit.com/circuitpython-with-esp32-quick-start/web-serial-esptool

I'm not sure where it's linked to on the site. It is referenced when there's a UF2 bootloader section. Maybe we could link to it for ESP32 boards without a UF2 bootloader in particular, since it's the main way to install the "Absolute Newest" and "Previous Versions" (outside of using esptool.py).

[tannewt]

CircuitPython.org is meant for CircuitPython. We don't want to have to support other random binaries.

[0wwafa]

CircuitPython.org is meant for CircuitPython. We don't want to have to support other random binaries.

@tannewt
I didn't mean random binaries, but for example the latest or previous versions.