fix(MessageMentions): add InGuild generic

[almeidx]

Please describe the changes this PR makes and why it should be merged:
Added a InGuild generic to the MessageMentions class to help narrow the types of #guild and #members

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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2 Ignored Deployments

Name	Status	Preview	Updated
discord-js	⬜️ Ignored (Inspect)		Nov 25, 2022 at 5:26PM (UTC)
discord-js-guide	⬜️ Ignored (Inspect)		Nov 25, 2022 at 5:26PM (UTC)

[codecov]

Codecov Report

Merging #8828 (217cdd3) into main (7e06f68) will decrease coverage by 1.03%.
The diff coverage is n/a.

❗ Current head 217cdd3 differs from pull request most recent head 1257e6c. Consider uploading reports for the commit 1257e6c to get more accurate results

@@            Coverage Diff             @@
##             main    #8828      +/-   ##
==========================================
- Coverage   86.64%   85.61%   -1.04%     
==========================================
  Files          92       96       +4     
  Lines        9029     9459     +430     
  Branches     1129     1134       +5     
==========================================
+ Hits         7823     8098     +275     
- Misses       1164     1319     +155     
  Partials       42       42              

Flag	Coverage Δ
brokers	65.24% <ø> (?)
builders	98.65% <ø> (ø)
collection	100.00% <ø> (ø)
proxy	81.53% <ø> (ø)
rest	91.97% <ø> (ø)
util	100.00% <ø> (ø)
utilities	100.00% <ø> (ø)
voice	63.70% <ø> (ø)
ws	59.83% <ø> (ø)

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

Impacted Files	Coverage Δ
packages/collection/src/collection.ts	100.00% <0.00%> (ø)
packages/brokers/src/brokers/redis/PubSubRedis.ts	84.48% <0.00%> (ø)
packages/brokers/src/brokers/redis/RPCRedis.ts	54.61% <0.00%> (ø)
packages/brokers/src/brokers/Broker.ts	96.51% <0.00%> (ø)
packages/brokers/src/brokers/redis/BaseRedis.ts	51.16% <0.00%> (ø)

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