[LoadingButton] Change LoadingButton prop pending to loading

[guillermaster]

This pull request renames the pending prop of the LoadingButton component to loading, as per issue

Closes #21593

[mui-pr-bot]

Details of bundle changes

Generated by 🚫 dangerJS against 5d5cd3d

[oliviertassinari]

I'm not sure the related issue had reached enough maturity to go to the implementation phase.

[mbrookes]

I'm not sure the related issue had reached enough maturity to go to the implementation phase.

The issue is marked as "good to take"...

[oliviertassinari]

@mbrookes True, why I reopened it. Do we want to move forward with this direction?

[mbrookes]

🍿

[guillermaster]

The pull request has been updated, the unit tests were fixed. The tests that were failing because the original code had an incorrect casing in these props: endIconLoadingEnd, startIconLoadingStart, and labelLoadingCenter.

[oliviertassinari]

OK, re-reading the linked issue a couple of weeks later, I think that we should go all-in on loading. The button isn't in a pending state that's the application or some task. However, the button displays a loader. So I think that that loading, even if not perfect is better, it better describes the state or the button (render a loader) which I think we should optimize for.

[oliviertassinari]

However, we didn't receive a clear approval in the team for going forward so closing both PR and issue. "No is temporary, yes is forever in open-source". @guillermaster thanks for spending time on it!