feat(Webhook)!: New classes PartialWebhook & PartialSyncWebhook

[Snipy7374]

Summary

• Closes GH-622

Extras:

• webhook/async_.py#L964-L971 moved __repr__ and url from Webhook and SyncWebhook to BaseWebhook to reduce code redundancy.
• webhook/sync.py#L644-L645 document when SyncWebhook.from_url() could raise a TypeError.

Checklist

• [x] If code changes were made, then they have been tested
  • [x] I have updated the documentation to reflect the changes
  • [x] I have formatted the code properly by running task lint
  • [x] I have type-checked the code by running task pyright
• [ ] This PR fixes an issue
• [x] This PR adds something new (e.g. new method or parameters)
• [x] This PR is a breaking change (e.g. methods or parameters removed/renamed)
• [ ] This PR is not a code change (e.g. documentation, README, ...)

[onerandomusername]

@Snipy7374 would you please resolve conflicts?

[Snipy7374]

@Snipy7374 would you please resolve conflicts?

Oke