External Components for ESPHome

[Hedda]

This code repo could maybe be rearranged directories into "components/serial_server" so can be pulled dynamically from ESPHome yaml

Note! Please also see thegroove/esphome-zeroconf#3

Maybe add link to readme files for reference once adjust the repos -> https://esphome.io/components/external_components.html

external_components:
  - source: github://thegroove/esphome-serial-server

serial_server:

PS: oxan has now done this in his repo for his "Stream server for ESPHome" -> https://github.com/oxan/esphome-stream-server