[WIP] feat(structures): add constants, utils, errors

[qwright10]

Please describe the changes this PR makes and why it should be merged: This PR is to track changes I have made/will make.

Status Work in progress

• [ ] Code changes have been tested against the Discord API, or there are no code changes

Semantic versioning classification:

• [x] This PR changes the library's interface (methods or parameters added)
  • [ ] This PR includes breaking changes (methods removed or renamed, parameters moved or removed)
• [ ] This PR only includes non-code changes, like changes to documentation, README, etc.

My notes/remarks: https://hasteb.in/upimotok.sql

[codecov[bot]]

Codecov Report

Merging #25 into master will not change coverage. The diff coverage is n/a.

@@            Coverage Diff            @@
##            master       #25   +/-   ##
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  Coverage   100.00%   100.00%           
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  Files            3         3           
  Lines          142       142           
  Branches        42        42           
=========================================
  Hits           142       142           

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