[material-ui][LinearProgress] Deprecate composed classes

[headironc]

part of 41282

• I have followed (at least) the PR section of the contributing guide.

[DiegoAndai]

Thanks for working on this @headironc!

A couple of this:

1. The MuiLinearProgress-bar1 and MuiLinearProgress-bar2 classes don't exist, we need to add them. When you add them, may I also ask you to add tests to check they're correctly applied? You can use this PR as a guide: https://github.com/mui/material-ui/pull/42281/files
2. May I also ask you to prepare a sandbox (You can use this one which uses this PR builds) testing that the deprecated classes are correctly replaced by the suggested compositions? For example:

In the sandbox, have two linear progress components, one with:

<LinearProgress
    sx={[`&.${linearProgressClasses.bar1Buffer}`]: {
        backgroundColor: 'red',
    }
/>

and another with:

<Drawer
    sx={[`&.${linearProgressClasses.buffer} > .${linearProgressClasses.bar1}`]: {
        backgroundColor: 'red',
    }
/>

And the result should be the same.

No need to do it with all the combinations, these should be enough:

• bar1Buffer
• bar1Determinate
• bar1Indeterminate
• bar2Buffer
• barColorPrimary
• dashedColorPrimary

[headironc]

@DiegoAndai Okay, I'll finish it.