Use emitc.ptrin VMToEmitC conversions (#8364)

* Add support for `emitc.ptr` type

* Use `emitc.ptr` in ListSetRefOpConversion

* Use `emitc.ptr` in ListSetOpConversion

* Use `emitc.ptr` in FailOpConversion

* Use `emitc.ptr` in GlobalLoadOpConversion

* Use `emitc.ptr` in GlobalStoreOpConversion

* Use `emitc.ptr` for `void*` type

* Use `emitc.ptr` for `void**` type

* Use `emitc.ptr` for `uint8_t*` type

* Use `emitc.ptr` for `iree_vm_stack_t*` type

* Use `emitc.ptr` for vm module pointer types

* Use `emitc.ptr` for `iree_vm_function_call_t*` type

* Use `emitc.ptr` for `iree_vm_execution_result_t*` type

* Use `emitc.ptr` for `iree_vm_function_t*` type

* Use `emitc.ptr` for `iree_vm_buffer_t*` type

* Use `emitc.ptr` for `iree_vm_module_state_t` pointer types

* Use `emitc.ptr` for `iree_vm_list_t` pointer types

* Use `emitc.ptr` for remaining pointer types

Refactors the remaining non-`iree_vm_ref_t` pointer types.