Refactor externref related APIs of reference types feature (#971)

Currently when calling wasm_runtime_call_wasm() to invoke wasm function
with externref type argument from runtime embedder, developer needs to
use wasm_externref_obj2ref() to convert externref obj into an internal ref
index firstly, which is not convenient to developer.
To align with GC feature in which all the references passed to
wasm_runtime_call_wasm() can be object pointers directly, we change the
interface of wasm_runtime_call_wasm() to allow to pass object pointer
directly for the externref argument, and refactor the related codes, update
the related samples and the document.

core/iwasm/common/wasm_runtime_common.h

@@ -525,11 +525,6 @@ bool
 wasm_runtime_call_indirect(WASMExecEnv *exec_env, uint32 element_indices,
                            uint32 argc, uint32 argv[]);
 
-bool
-wasm_runtime_create_exec_env_and_call_wasm(
-    WASMModuleInstanceCommon *module_inst, WASMFunctionInstanceCommon *function,
-    uint32 argc, uint32 argv[]);
-
 bool
 wasm_runtime_create_exec_env_singleton(WASMModuleInstanceCommon *module_inst);
 
@@ -813,16 +808,6 @@ wasm_runtime_dump_module_inst_mem_consumption(
 void
 wasm_runtime_dump_exec_env_mem_consumption(const WASMExecEnv *exec_env);
 
-#if WASM_ENABLE_REF_TYPES != 0
-void
-wasm_runtime_prepare_call_function(WASMExecEnv *exec_env,
-                                   WASMFunctionInstanceCommon *function);
-void
-wasm_runtime_finalize_call_function(WASMExecEnv *exec_env,
-                                    WASMFunctionInstanceCommon *function,
-                                    bool ret, uint32 *argv);
-#endif
-
 bool
 wasm_runtime_get_export_func_type(const WASMModuleCommon *module_comm,
                                   const WASMExport *export_, WASMType **out);