Add tests and integrate to CI

[pocc]

Problem

This application lacks python or PyQt5 testing.

Description

• This app needs unit tests in order to prevent bugs before they happen
• Tests should be both for individual functions and for GUI testing
• Tests should fuzz
• All tests should be scripts that CI can call

  Possible Resources

• PyQt Unit Tests
• PyQtTester
• Python Unit Test examples

[pocc]

Depends on more merlink.py functions being in more modules so that unit tests can be written. Marking as blocked by #30.