devcontainer: minor fixes for nodesource and npm packages

[jasisk]

• nodesource is deprecating the old install script. Running it right now introduces a 60s delay and will eventually break
• a few npm packages are required globally to run the just commands—I've set them to the latest versions as of today

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (66b4799) 77.66% compared to head (78d94da) 85.22%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1124      +/-   ##
==========================================
+ Coverage   77.66%   85.22%   +7.56%     
==========================================
  Files         137      137              
  Lines       12593    12593              
==========================================
+ Hits         9780    10733     +953     
+ Misses       2813     1860     -953     

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