have presubmit.cfg in separate node* folders

[jkwlui]

Fixes #<issue_number_goes_here> (it's a good idea to open an issue first for discussion)

• Tests and linter pass
• Code coverage does not decrease (if any source code was changed)
• Appropriate docs were updated (if necessary)

[codecov]

Codecov Report

Merging #151 into master will not change coverage.
The diff coverage is n/a.

@@          Coverage Diff          @@
##           master   #151   +/-   ##
=====================================
  Coverage     100%   100%           
=====================================
  Files           2      2           
  Lines          83     83           
=====================================
  Hits           83     83

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