move_item_up/down crashes if there's a table in the widget tree

## Version of Dear PyGui

Version: 1.10.1
Operating System: Windows 10

## My Issue/Question

If `move_item_up` or `move_item_down` is used on a widget that resides somewhere below a table in the widgets tree (as seen by the depth-first tree lookup), DPG crashes on the `move_item_YYY` call.

The reason is that `MoveChildUp/Down` functions in `mvItemRegistry.cpp` perform a depth-first lookup on the widgets tree, comparing each item's UUID to the specified UUID - that is, instead of using `GetItem` they search for the target object on their own. This is because they need to manipulate the parent object (the list of children in it). The following line of code does not expect `child` to be null:

```cpp
if (child->uuid == uuid)
```

On the other hand, `mvTable` adds null pointers to slot 2 each time a column is added. I couldn't find why it does that and how slot 2 is used afterwards (it's reserved for draw commands, but why a column needs null at the corresponding location in slot 2?).

```cpp
void mvTable::onChildAdd(std::shared_ptr item)
{

if (item->type == mvAppItemType::mvTableColumn)
{
...
childslots[2].push_back(nullptr);
```

When `MoveChildUp/Down` perform their lookup, they stumble upon those `nullptr`'s in slot 2 of the table. Boom.

## To Reproduce

Steps to reproduce the behavior:
1. Run the example below. It crashes right at startup.

## Expected behavior

No crash.

## Screenshots/Video

None.

## Standalone, minimal, complete and verifiable example

```python
import dearpygui.dearpygui as dpg

dpg.create_context()
dpg.setup_dearpygui()
dpg.create_viewport(title="Test", width=600, height=600)

with dpg.window():
with dpg.table():
dpg.add_table_column()

btn = dpg.add_text("Lorem")
dpg.move_item_up(btn)

dpg.show_viewport()
dpg.start_dearpygui()
dpg.destroy_context()
```