feat(Sticker): add support for gif stickers

[almeidx]

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

• GIF Sticker image format support discord/discord-api-docs#5833

Depends on:

• feat(StickerFormatType): add GIF discord-api-types#688

Status and versioning classification:

• I know how to update typings and have done so, or typings don't need updating

[vercel]

The latest updates on your projects. Learn more about Vercel for Git ↗︎

Name	Status	Preview	Comments	Updated
discord-js	✅ Ready (Inspect)	Visit Preview	💬 Add your feedback	Jan 13, 2023 at 3:23PM (UTC)
discord-js-guide	✅ Ready (Inspect)	Visit Preview	💬 Add your feedback	Jan 13, 2023 at 3:23PM (UTC)

[codecov]

Codecov Report

Merging #9038 (7bc1221) into main (1831aca) will decrease coverage by 0.00%.
The diff coverage is 100.00%.

❗ Current head 7bc1221 differs from pull request most recent head 1550120. Consider uploading reports for the commit 1550120 to get more accurate results

@@            Coverage Diff             @@
##             main    #9038      +/-   ##
==========================================
- Coverage   84.11%   84.11%   -0.01%     
==========================================
  Files         108      108              
  Lines        9489     9488       -1     
  Branches     1113     1113              
==========================================
- Hits         7982     7981       -1     
  Misses       1466     1466              
  Partials       41       41              

Flag	Coverage Δ
brokers	66.36% <ø> (ø)
builders	98.25% <ø> (ø)
collection	100.00% <ø> (ø)
next	0.00% <ø> (ø)
proxy	79.56% <ø> (ø)
rest	92.06% <100.00%> (-0.01%)	⬇️
util	98.42% <ø> (ø)
utilities	100.00% <ø> (ø)
voice	63.77% <ø> (ø)
ws	59.49% <ø> (ø)

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

Impacted Files	Coverage Δ
packages/rest/src/lib/CDN.ts	97.73% <100.00%> (-0.01%)	⬇️
packages/rest/src/lib/utils/constants.ts	98.21% <100.00%> (ø)

📣 We’re building smart automated test selection to slash your CI/CD build times. Learn more

[kyranet]

Minor nits, the map is a pseudo-enum, so it needs to be named in PascalCase, as the rest of the constants from the Constants file (https://github.com/discordjs/discord.js/blob/05a1cbfe5479195b0bc9b6f0971fe39f6af6fd77/packages/discord.js/src/util/Constants.js).

Also, shouldn't we export this (in the Constants file) so users can map the extensions themselves?

[kyranet]

Sorry, I Ctrl+Enter'd instead of clicking "Request changes". ↑