Support getting global type from `wasm_runtime_get_import_type` and
`wasm_runtime_get_export_type`, and add two APIs:
```C
wasm_valkind_t
wasm_global_type_get_valkind(const wasm_global_type_t global_type);
bool
wasm_global_type_get_mutable(const wasm_global_type_t global_type);
```