feat(Interactions): add InteractionWebhook for better internals

[ckohen]

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

Currently, interactions create a WebhookClient for handling additional response to the interaction. This works great, except for a few places, such as InteractionResponses#followUp which has to be done without the WebhookClient due to APIMessage not resolving ephemeral as a valid option.

This PR creates an InteractionWebhook, which allows APIMessage to resolve isInteraction more accurately and allows the removal of the inapplicable methods.

Since this PR is touching all of the webhook handling, I have also added the empty functions to the bottom of WebhookClient to allow them to be documented properly.

⚠️ The base for this PR is #5674 as it refactors interactions quite a bit, this will be rebased to master once 5674 is merged.

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
• This PR changes the library's interface (methods or parameters added)
• This PR includes breaking changes (methods removed or renamed, parameters moved or removed)

[SpaceEEC]

Keeping this a draft until #5674 is merged then.

[ckohen]

🤦 I definitely thought I created it as draft, ty.

[iCrawl]

This needs a rebase @ckohen