Inspecting ModalBottomSheet

When we call `showModalBottomSheet` to show a bottom sheet, It's a little hard to select a widget that exists in the bottom sheet, the inspector selects a widget behind the sheet and we must try and error multiple times to select a widget inside of bottom sheet

I think this is true for dialogs too

Start by reproducing the issue with showModalBottomSheet and inspect how widget selection behaves when the sheet or a dialog is visible. Done means the inspector can reliably select widgets inside the bottom sheet and dialogs instead of selecting widgets behind them.

Written by the indexing model from the issue text.