feat: expose https agent options

[ckohen]

Please describe the changes this PR makes and why it should be merged:

Ported from discordjs/discord.js#6177

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
• This PR changes the library's interface (methods or parameters added)

[codecov]

Codecov Report

Merging #82 (030aa77) into main (6df603e) will increase coverage by 0.07%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main      #82      +/-   ##
==========================================
+ Coverage   88.83%   88.91%   +0.07%     
==========================================
  Files           8        8              
  Lines        1344     1353       +9     
  Branches      142      142              
==========================================
+ Hits         1194     1203       +9     
  Misses          9        9              
  Partials      141      141              

Impacted Files	Coverage Δ
packages/rest/src/lib/REST.ts	96.27% <100.00%> (+0.10%)	⬆️
packages/rest/src/lib/RequestManager.ts	93.92% <100.00%> (+0.03%)	⬆️
packages/rest/src/lib/utils/constants.ts	100.00% <100.00%> (ø)

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