Add a clone example

[lum1n0us]

Use a clone example to show

• cold start and warm start
• how to clone from wasm_module_t and bypass loading phase

It turns out that there is a strong requirement of almost everything in wasm_instantiate() except funciton related if do a clone of wasm_instance_t.

Since we tend to isolate user data in threads, it needs to malloc and initialie

• global. WASMGlobalIntance and global data
• memory. WAAMMemoryInstance, memory_data and heap
• table. WASMTableInstance, table_data
• exports. all global, memory and table