feat: support form-data and octet-streams in remaining adapters

[Nick-Lucas]

Describe the feature you'd like to request

#5613 added support for FormData and Blob/File/Uint8array Octet Streams, but only in the node-http adapters (standalone, express, nextjs)

Other adapters only received JSON support but are now extensible to support additional content types

Describe the solution you'd like to see

• Fetch: form-data
• Fetch: octets
• Fastify: form-data
• Fastify: octets
• Lambda: form-data
• Lambda: octets
• Next AppRouter: form-data
• Next AppRouter: octets

These don't need to all be done at once, folk from the community should feel free to contribute just one at a time for their own needs

Describe alternate solutions

No

Additional information

No response

👨‍👧‍👦 Contributing

• 🙋‍♂️ Yes, I'd be down to file a PR implementing this feature!

Funding

• You can sponsor this specific effort via a Polar.sh pledge below
• We receive the pledge once the issue is completed & verified