Improve debugger experience #2710

Meta issue to track issues that can/need to be resolved in order to provide a better debugger experience:

• Ensure file being debugged is a python file (Display message if active file being debugged is not a python file #1178)
• Auto select best debug config item based on workspace (Auto select relevant debug configuration based on files in project #1179)
• Provide meaningful error message (UI) when flask app is not configured correctly (Bump ua-parser-js from 0.7.20 to 0.7.28 DonJayamanne/pythonVSCode#1670)
• Provide meaningful error message (UI) when django app is not configured correctly (Provide meaningful error message (UI) when django app is not configured correctly #1671)
• Look into issues related to path mappings and case sensitive paths with debugger Debugger issues related to path mappings and case sensitive paths #2976 VS Code opening duplicate window with remote debugging and live reloading #3185
• Ensure users do not select the executable pythonw.exe instead of python.exe
• Automatically infer local and remote path mappings for remote debugging (Automatically infer local and remote path mappings for remote debugging #1385)
• Show files that can be used for configuring Flask/Django applications (#7631)