Only use node-red audit events to update local package list

[knolleary]

This fixes how we track what additional modules have been installed in Node-RED.

When this was originally added, it was done in response to Node-RED writing its settings to the database - which includes a list of modules it has loaded.

We then added the ability to do this by listening to the audit events that get sent (nodes.install for eg).

We have found a flaw in the logic of the first approach when a module is removed. There is a sequence where Node-RED rewrites its settings before it discovers the removed module is gone - causing the module to get added back to the package list.

On review, I've determined we don't need to rely on this mechanism - we can base it entirely on the audit events. So this PR removes this first mechanism.

Whilst there, I've also added support for the modules.install event that was added in Node-RED 3.1.1 - this is triggered when the Function node installs a module. This allows us to add those modules to the package list so they get reinstalled as part of the initial dependency install and not rely on Node-RED dynamically reinstalling them.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (a9b1fee) 40.20% compared to head (14feece) 40.19%.
Report is 7 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3189      +/-   ##
==========================================
- Coverage   40.20%   40.19%   -0.02%     
==========================================
  Files         582      582              
  Lines       21352    21368      +16     
  Branches     5137     5141       +4     
==========================================
+ Hits         8584     8588       +4     
- Misses      12768    12780      +12     

Flag	Coverage Δ
backend	76.17% <100.00%> (-0.05%)	⬇️
frontend	1.97% <0.00%> (-0.01%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.