Simplify SDK with go:wasmexport

### Feature description

The Processor SDK is currently communicating with Conduit through a "command-and-response" loop, where the Processor SDK runs a loop in which it asks Conduit for a new command to execute. The commands are actually processor methods, e.g. `Open`, `Process`, etc. The reason for this is that WASM modules that are written in Go cannot export functions.

However, the go:wasmexport directive is going to be added to Go 1.24. Using this directive and simply exporting all of the processor methods would simplify our code.