Increase maximum module files payload using protobuf streams

Problem

Coder has a4MB protobuf message size limit that prevents templates with large Terraform modules from being processed. When dynamic parameters require module files from~/.terraform/modules that exceed this limit, template creation fails.

Solution

This PR implements protobuf streaming to handle large module files by:

1. Streaming large payloads: When module files exceed the 4MB limit, they're streamed in chunks using a new UploadFile RPC method
2. Database storage: Streamed files are stored in the database and referenced by hash for deduplication
3. Backward compatibility: Small module files continue using the existing direct payload method

Key Changes

• New protobuf streams: Added UploadFile RPC and DataUpload/ChunkPiece message types
• Smart fallback: Automatically detects oversized payloads and switches to streaming
• File deduplication: Module files are deduplicated per template version using content hashes
• Testing: Added test coverage for the streaming upload functionality.

Architecture

• Coderd↔️ Provisionerd: Uses new streaming RPC when payload exceeds limits.
  

  coder/provisionerd/proto/provisionerd.proto

  Lines 220 to 222 ine880894

  	// UploadFile streams files to be inserted into the database.
  	// The file upload_type should be used to determine how to handle the file.
  	rpcUploadFile(streamUploadFileRequest)returns (Empty);

• Provisionerd↔️ Provisioner: Extends existing stream with new message types for in-memory communication

This change enables templates with arbitrarily large Terraform modules while maintaining performance through deduplication and preserving the existing fast path for smaller payloads.

TODO:

• Bump protobuf versions
• Implement backwards compatible?
  • Do not upload large files to old coderds
• Verify forward compatible
• Add e2e test with a large module

Things that I wish I could change

• We have 2 proto files, and they have overlapping types. IdeallyDataUpload andChunk would be defined in 1 place and have their types reusable in both contexts 😢.