Add log messages for device agent connect/disconnect events

[knolleary]

Description

Adds log events for when the device agent tunnel connects/disconnects and when editor websocket connections connect/disconnect.

We previously had audit event log entries for when the editor mode was enabled - but that didn't report on the websocket events.

This will give better insight on the reliability of the websocket tunnels.

Related Issue(s)

Checklist

• I have read the contribution guidelines
• Suitable unit/system level tests have been added and they pass
• Documentation has been updated
  • Upgrade instructions
  • Configuration details
  • Concepts
• Changes flowforge.yml?
  • Issue/PR raised on flowforge/helm to update ConfigMap Template
  • Issue/PR raised on flowforge/CloudProject to update values for Staging/Production

Labels

• Backport needed? -> add the backport label
• Includes a DB migration? -> add the area:migration label

[codecov]

Codecov Report

Merging #2507 (4b02fe2) into main (6582372) will increase coverage by 72.80%.
The diff coverage is 50.00%.

@@            Coverage Diff             @@
##            main    #2507       +/-   ##
==========================================
+ Coverage   1.55%   74.36%   +72.80%     
==========================================
  Files        489      224      -265     
  Lines      17129     8854     -8275     
  Branches    3968     1822     -2146     
==========================================
+ Hits         266     6584     +6318     
+ Misses     16863     2270    -14593     

Flag	Coverage Δ
backend	74.36% <50.00%> (?)
frontend	?

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

Impacted Files	Coverage Δ
forge/ee/lib/deviceEditor/DeviceTunnelManager.js	69.46% <50.00%> (+69.46%)	⬆️

... and 441 files with indirect coverage changes