feat: allow sending of basic files through webhooks

[zaida04]

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

Status

• Code changes have been tested.

Semantic versioning classification:

• 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]

🦋 Changeset detected

Latest commit: 3a7d5fd

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

This PR includes changesets to release 6 packages

Name	Type
@guildedjs/guilded-api-typings	Patch
@guildedjs/rest	Patch
@guildedjs/webhook-client	Minor
guilded.js	Patch
@guildedjs/ws	Patch
@guildedjs/gil	Patch

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