[slider] Show value tooltip when hovering a slider thumb with disableSwap true

Duplicates

• I have searched the existing issues

Latest version

• I have tested the latest version

Summary 💡

Hovering on a slider thumb should make a tooltip with the thumb's value pop out when valueLabelDisplay is set to auto and disableSwap is set. Just like it does when disableSwap is not set.

Examples 🌈

https://codesandbox.io/s/pensive-dream-w91mx?file=/src/App.js

In this example, the only difference between the two sliders is that disableSwap is set on the second one.
A tooltip showing the value of the thumb should pop out when hovering on the thumb regardless of whether disableSwap is set or not.

Motivation 🔦

I don't think that setting disableSwap should change the behavior of valueLabelDisplay.
It is unexpected and makes disableSwap unusable when you need to maintain the ability to show the thumbs' value on hover.

I thought it was a bug at first, but it seem it may have been the intended behavior (https://github.com/mui-org/material-ui/pull/25547#pullrequestreview-623291082), so I'm filing a feature request instead.

I could take a stab at it.

Start with the /src/App.js example in the linked CodeSandbox and compare the two sliders, focusing on valueLabelDisplay="auto" with and without disableSwap. Done means hovering either thumb shows its value tooltip in both configurations without changing the existing disableSwap behavior.