[docs] Sort Pickers & Charts API slots alphabetically

[LukasTy]

Once again api:docs generation results have become flaky and sometimes keep failing in CI: https://app.circleci.com/pipelines/github/mui/mui-x/61920/workflows/b0db904d-129e-4379-9d5d-e7f23d837aea/jobs/353446.
Sorting them alphabetically would ensure this wouldn't happen. 🤔

Also added the same sorting for the Charts package based on: #13843 (comment)

[mui-bot]

Deploy preview: https://deploy-preview-13843--material-ui-x.netlify.app/

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[JCQuintas]

I think this would be useful for charts as well 👍

[LukasTy]

I think this would be useful for charts as well 👍

I just wanted to let you know, that flakiness has been observed only for Pickers previously and now again. 🤔
Would you like me to add the sort for it? 🤔
WDYT @alexfauquette?
What about @mui/xgrid? Do you like the existing order or do you feel having slots in alphabetical order would make more sense? 🤔

[JCQuintas]

We see it on charts too, the flakiness

[LukasTy]

We see it on charts too, the flakiness

Oh, sorry, I didn't notice it then. 🙈

[JCQuintas]

@LukasTy it usually happens in the pull request themselves when we change import orders. Sometimes it creates a chain effect that changes a lot of files :(

[LukasTy]

it usually happens in the pull request themselves when we change import orders. Sometimes it creates a chain effect that changes a lot of files :(

Gotcha. I've added Charts to the sorted list. 😉
Let's wait for @alexfauquette and Grid input. 🤞

[alexfauquette]

It's ok for charts 👍

Thanks for taking care of it :)