Feature/comp 114 python code quality

Various python code quality and readability improvements Noteworthy are:

• The db model upgrade to the sqlalchemy2 syntax, giving full type information. NB the package types-sqlalchemy has to be removed, potentially also from the servers if it doesnt happen automatically (this package is only intended for sqlalchemy 1.4, sqlalchemy2 has its type info included).
• The use of a new package sphinxcontrib-httpdomain for more conveniently documenting the api endpoints in sphinx
• SURVEY_DATABASE_URI is still a required config entry, but as the format isn't checked, it can be left empty, as in the config-example.json file. Should be clear enough.