feat(client): unify fetch and node clients

[jordanshatford]

NOTE: node-fetch was made to replicate the Fetch API, rather than duplicating all templates (as we plan to eventually move away from templates), I have combined them with flags in the only places that differ (import from node-fetch and credentials as node-fetch doesnt support those)

This will be also nice as node client is legacy, AND fetch will eventually be supported fully in node (21) and is already experimental since our lowest supported version (node 18)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 91.84%. Comparing base (cefbda4) to head (80a5886).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #185      +/-   ##
==========================================
- Coverage   91.87%   91.84%   -0.03%     
==========================================
  Files          66       66              
  Lines        3949     3935      -14     
  Branches      476      476              
==========================================
- Hits         3628     3614      -14     
  Misses        320      320              
  Partials        1        1              

Flag	Coverage Δ
unittests	91.84% <ø> (-0.03%)	⬇️

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