run web interface standalone with a mock API server

[proddy]

When developing and testing the web interface, it's handy not to bother with reflashing an ESP32 each time. The idea is to mimic the ESP using a mock/stub server that responds to HTTP POST and GET requests.

Currently a first draft at this is in the ft_mockapi branch. To run it do

% cd interface
% npm run dev

The hardcoded data is limited at the moment and can be easily extended by changing the file /mock-api/server.js

[bbqkees]

I tried it and it looks great.

One thing: I got an error during the build; had to install the express module, and then it worked fine.

To install Express:
npm install express

[proddy]

fixed that and updated the doc. https://github.com/emsesp/EMS-ESP32/blob/ft_mockapi/mock-api/README.md

[proddy]

merged into dev