feat(Rest): use native Node.js AbortController

[J-Human]

Please describe the changes this PR makes and why it should be merged:
Node.js already has an AbortController implementation, hence a poly fill is no longer needed.

Status and versioning classification:

• Code changes have been tested against the Discord API, or there are no code changes
• I know how to update typings and have done so, or typings don't need updating

[codecov]

Codecov Report

Merging #66 (4298ada) into main (65cb8e2) will decrease coverage by 0.01%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main      #66      +/-   ##
==========================================
- Coverage   85.84%   85.82%   -0.02%     
==========================================
  Files           8        8              
  Lines        1010     1009       -1     
  Branches      101      101              
==========================================
- Hits          867      866       -1     
  Misses         42       42              
  Partials      101      101              

Impacted Files	Coverage Δ
...ackages/rest/src/lib/handlers/SequentialHandler.ts	83.02% <ø> (-0.08%)	⬇️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 65cb8e2...4298ada. Read the comment docs.