feat: merge webhook-client into rest

[zaida04]

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

Status

• [x] Code changes have been tested.

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.

[changeset-bot[bot]]

🦋 Changeset detected

Latest commit: 2912ffbecd6d923393260a551e6d717c0ea6ed9a

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 4 packages

| Name | Type | | ------------------------ | ----- | | guilded.js | Patch | | @guildedjs/rest | Minor | | @guildedjs/gil | Patch | | @guildedjs/proxy-service | Patch |

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