easier tracking code debugging

[diosmosis]

Troubleshooting tracker problems caused by other WordPress plugins is currently painful and very much not user friendly. It requires having users:

• email support
• ask the user to set the tracker debug mode setting to "debug on demand"
• have a dev or support team member then manually send tracking requests to Matomo for WordPress to collect debug output
• ask the user to unset the tracker debug mode setting

This process can be simplified greatly by:

• only allow "debug on demand" as an option for the tracker debug mode setting
• when this setting is enabled:
  • set the tracker debug/debug on demand setting
  • add some debug code to the JavaScript tracker that will send the correct debug parameter if mtm_debug=1 is found in the current website URL
  • only allow tracker debugging if the current user is a Matomo admin
  • send tracker debug output to the WordPress debug.log file

Tracker debug information can then be obtained by having users:

• enable WP_DEBUG/WP_DEBUG_LOG (can be removed if we save the tracker debug output to a database field)
• enable the tracker debug mode setting
• perform some visits on the website while logged in
• send the tracker debug.log file (or collect debug output via the MWP admin UI) to support