[Checkbox] Migrate to emotion

[natac13]

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

#24405

[mui-pr-bot]

@material-ui/core: parsed: +0.07% , gzip: +0.03%

Details of bundle changes

Generated by 🚫 dangerJS against b13b4e6

[natac13]

I was curious if the indeterminate class is really a Pseudo class as it's name is differenent than other Pseudo classes

https://next--material-ui.netlify.app/api/checkbox/#css

https://github.com/mui-org/material-ui/pull/24702/files#diff-648f4c502fda26c52fcb02385dcdf3c032b5aea842cfd1df85ab673f5058d239R27

[natac13]

I think the failing test just need to be re-run.

[vicasas]

Maybe for the first failed test you are missing themeVariants in the test file skip. I previously had a similar error and solved it using this.

[natac13]

I do not think these test have to do with the changes I have made. I could be wrong. But they have been failing intermittently

Ill add it and find out though thanks for the help.
Update:
Just checked again and I do not see those errors.

[oliviertassinari]

@natac13 We could in theory treat indeterminate as the other pseudo-classes. However, the LinearProgress already uses this name. It would create a conflict. For now, I think that we can focus on the migration :)