[DataGrid] Refactor/Remove ColumnReorderApi

[dtassone]

Summary 💡

Those methods attached to apiRef are actually event handlers and should not be on apiRef.
ApiRef goal is to allow users to manipulate the grid.
startResizeOnMouseDown, onColItemDragStart, onColHeaderDragOver... are not meaningful.

Something like options.onColumnResize or options.onColumnReordered are more appropriate.
To get the effect required by those methods, we can just publish the event from the component and subscribe to the event in the hook to handle it.

We can also provide a setColumnWidth method on the api that would allow to only update the col width, using the state, and firing onColumnResize once done.

Similarly we can provide a setColumnIndexmethod on the api that would allow to update the col position, using the state, and firing onColumnReorder event once done.

related to #1167

[DanailH]

I agree. There was a similar request for having an onColumnReordered on the grid itself.

[bushev]

Hey @DanailH,

The feature is quite essential for our app. What's the approximate ETA?

[dtassone]

FYI @m4theushw is going to refactor onColumnReorder as part of #1250

We can create a separate issue for onColumnResize