feat: add @discordjs/util

[suneettipirneni]

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

Adds an internal package for utilities and types that are shared among @discordjs packages.

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

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1 Ignored Deployment

Name	Status	Preview	Updated
discord-js	⬜️ Ignored (Inspect)		Oct 2, 2022 at 5:51PM (UTC)

[codecov]

Codecov Report

Merging #8591 (f4b6b3b) into main (3f86561) will decrease coverage by 5.24%.
The diff coverage is 100.00%.

❗ Current head f4b6b3b differs from pull request most recent head bab0130. Consider uploading reports for the commit bab0130 to get more accurate results

@@            Coverage Diff             @@
##             main    #8591      +/-   ##
==========================================
- Coverage   92.09%   86.84%   -5.25%     
==========================================
  Files          10       87      +77     
  Lines        2099     8811    +6712     
  Branches      239     1103     +864     
==========================================
+ Hits         1933     7652    +5719     
- Misses        163     1117     +954     
- Partials        3       42      +39     

Flag	Coverage Δ
builders	100.00% <100.00%> (?)
collection	100.00% <ø> (?)
proxy	80.46% <ø> (?)
rest	92.07% <100.00%> (-0.02%)	⬇️
util	100.00% <100.00%> (?)
utilities	100.00% <ø> (?)
voice	63.83% <ø> (?)
ws	59.86% <100.00%> (?)

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
packages/util/src/Equatable.ts	100.00% <ø> (ø)
packages/util/src/JSONEncodable.ts	100.00% <ø> (ø)
packages/builders/src/components/Component.ts	100.00% <100.00%> (ø)
...ders/src/components/selectMenu/SelectMenuOption.ts	100.00% <100.00%> (ø)
...ges/builders/src/components/textInput/TextInput.ts	100.00% <100.00%> (ø)
packages/builders/src/interactions/modals/Modal.ts	100.00% <100.00%> (ø)
packages/rest/src/lib/RequestManager.ts	90.26% <100.00%> (-0.08%)	⬇️
packages/util/src/functions/lazy.ts	100.00% <100.00%> (ø)
packages/util/src/functions/range.ts	100.00% <100.00%> (ø)
packages/util/src/types.ts	100.00% <100.00%> (ø)
... and 80 more

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[imranbarbhuiya]

add in labels file and workflow matrix

[kyranet]

This new package should have tests, some are available in @sapphire/utilities such as lazy, which has their tests here.

Type-only utilities can be tested with Vitest's type assertions, doing expect<T>(assertedValue); or using tsd like discord.js does.

[kyranet]

Also, is .test-d.ts an accepted (and recognised) format? Or is it run only by TSD and not by Vitest?