Update telemetry in interface.nodes on receiving device metrics packets

[ianmcorvidae]

This is what we're doing for positions, and in the 2.5 branch, for admin messages. This should mean that for longer-lived processes, the node deviceMetrics field will have values that update.

[codecov]

Codecov Report

Attention: Patch coverage is 11.11111% with 8 lines in your changes missing coverage. Please review.

Project coverage is 61.48%. Comparing base (0813e8d) to head (78d8403).
Report is 2 commits behind head on master.

Files with missing lines	Patch %	Lines
meshtastic/__init__.py	11.11%	8 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #667      +/-   ##
==========================================
- Coverage   61.60%   61.48%   -0.13%     
==========================================
  Files          24       24              
  Lines        3584     3593       +9     
==========================================
+ Hits         2208     2209       +1     
- Misses       1376     1384       +8     

Flag	Coverage Δ
unittests	61.48% <11.11%> (-0.13%)	⬇️

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