[Fixup] Python examples should follow best practices

[kadler]

What improvement(s) could be made?

• Remove dead developerWorks Wiki links
• Example docs should use virtual environments
• bottle-example should be removed or mention that Flask is more widely used and point them to the Flask example
• xlsxwriter can now use the yum pyodbc package instead of building from source
• Flask example should use standard Flask ways of running, ie. flask run: https://flask.palletsprojects.com/en/2.2.x/quickstart/
• Flask example should use recommended layout: https://flask.palletsprojects.com/en/2.2.x/tutorial/layout/