Refactor module loading API using Config-based entrypoint

[jtakakura]

Summary

This PR refactors the WasmModule loading API to consolidate various loading parameters into a single Config structure, as proposed in #29. This change simplifies the API surface and ensures that all resource limits are applied consistently before module execution.

Major Changes

• Unified Loading API: Introduced WasmModule.Config and loadWithOptions in src/types.zig. This replaces multiple specialized load functions with a single, extensible entry point.
• Pre-execution Resource Limits: VM settings such as fuel, timeout, and memory limits are now applied before the module's start function or instantiation logic runs.
• C API Expansion: Added zwasm_config_t setter functions for fuel, timeout, and memory limits, allowing C users to configure VM constraints before module creation.
• Internal Migration: Updated the CLI and internal component logic to use the new unified API.

Rationale

The previous loading API was becoming complex as more configuration options were added. By moving parameters into a Config struct, we provide a cleaner interface for embedders and a more robust foundation for future features, such as execution cancellation.

This refactoring is a prerequisite for the cancellation mechanism currently in draft at #28.

Related Issue
Closes #29