Use ICOstate Library

[sanssecours]

Description

The current version of ICOapi in the main branch already uses ICOstate as library for handling most of the ICOtronic functionality. While the current version of the tests work, it is not clear, if the untested functionality still work as expected. To make sure that this is the case we should add more tests.

Current State

Endpoint	Code	Test	Note
stu	✅	✅
stu/reset	✅	✅
stu/connected	✅	✅
sth	✅	✅
sth/connect	✅	✅
sth/disconnect	✅	✅
sth/rename	✅	✅
sth/read-adc	✅	✅
sth/write-adc	✅	✅
state	✅	✅
state	✅	✅	WebSocket
reset-can	✅	✅