TST: Fix test suite

[tangkong]

Expected Behavior

• fix test suite warnings (font-awesome deprecations, in particular)
• fix test suite QThread teardown issues on TravisCI

Related to testing but not the test suite directly:

• Add an option to load a lightpath using the simulated database.

Possible Solution

qtbot is used in every gui-related test case, so we should be cleaning up widgets.

We suspected the typhos detailed screens were the culprit, but explicitly adding those widgets didn't seem to fix the issue.

it's also very possible I just missed something because I'm bad with qt

Steps to Reproduce (for bugs)

QThread teardown issues only occur on TravisCI, otherwise just try running pytest

-- Docs: https://docs.pytest.org/en/stable/how-to/capture-warnings.html
====================== 26 passed, 202 warnings in 15.45s =======================
QThread: Destroyed while thread is still running
/home/travis/.travis/functions: line 122:  5743 Aborted                 python run_tests.py
The command "if command -v coverage; then
    if [ -f "run_tests.py" ]; then
        coverage run --concurrency=thread --parallel-mode run_tests.py
    else
        coverage run --concurrency=thread --parallel-mode -m pytest
    fi
    (coverage combine && coverage report | grep -v -e ' 0%') || true
else
    if [ -f "run_tests.py" ]; then
        python run_tests.py
    else
        python -m pytest
    fi
fi
" exited with 134.
after_failure.1
0.00s$ LOGFILE="${AFTER_FAILURE_LOGFILE:-logs/run_tests_log.txt}"
after_failure.2
0.00s$ if [ -f "${LOGFILE}" ]; then
      cat "${LOGFILE}"
    else
      echo "Logfile ${LOGFILE} not found"
    fi
Logfile logs/run_tests_log.txt not found
Done. Your build exited with 1.

Context

Various test suite issues were glossed over during #133

Your Environment

pcds-5.4.1 + #133

[tangkong]

--sim option added in #141

[tangkong]

QThread issue should be fixed in https://github.com/pcdshub/typhos/pull/516