## Description

This PR introduces `DefaultSelectionStyle.mouseCursor` to configure the mouse cursor over selectable text.
It also applies this solution to `InkResponse` to make the mouse cursor win over the default one provided by selectable `Text` for many Material components (such as buttons). 

### Before

https://user-images.githubusercontent.com/840911/233627729-ddf98e2a-444d-4c6d-a6d5-f521982f48dd.mov

### After

https://user-images.githubusercontent.com/840911/233627718-8871a68f-d33c-44cf-b4a1-91bb1fcdf076.mov

## Related Issue

Fixes https://github.com/flutter/flutter/issues/104595

## Tests

Adds 6 tests.