Remove unused argument in wasm_runtime_lookup_function and refactor WASMModuleInstance (#3218)

Remove the unused parameter `signature` from `wasm_runtime_lookup_function`.

Refactor the layout of WASMModuleInstance structure:
- move common data members `c_api_func_imports` and `cur_exec_env` from
  `WASMModuleInstanceExtraCommon` to `WASMModuleInstance`
- In `WASMModuleInstance`, enlarge `reserved[3]` to `reserved[5]` in case that
  we need to add more fields in the future

ps.
https://github.com/bytecodealliance/wasm-micro-runtime/issues/2530
https://github.com/bytecodealliance/wasm-micro-runtime/issues/3202

core/iwasm/common/wasm_memory.c

@@ -823,13 +823,11 @@ return_func:
 
 #if WASM_ENABLE_INTERP != 0
         if (module->module_type == Wasm_Module_Bytecode)
-            exec_env =
-                ((WASMModuleInstanceExtra *)module->e)->common.cur_exec_env;
+            exec_env = ((WASMModuleInstance *)module)->cur_exec_env;
 #endif
 #if WASM_ENABLE_AOT != 0
         if (module->module_type == Wasm_Module_AoT)
-            exec_env =
-                ((AOTModuleInstanceExtra *)module->e)->common.cur_exec_env;
+            exec_env = ((AOTModuleInstance *)module)->cur_exec_env;
 #endif
 
         enlarge_memory_error_cb(inc_page_count, total_size_old, 0,