[Switch] Make color primary default

[vicasas]

Breaking changes

• [Switch] Make color="primary" the default over secondary. This better matches the material design guidelines.

  -<Switch />
  +<Switch color="secondary" />

---

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

One of the material design section #20012

Preview: https://deploy-preview-26182--material-ui.netlify.app/components/switches/

[mui-pr-bot]

Details of bundle changes (experimental)

Generated by 🚫 dangerJS against 70e1166

[mnajdova]

Let’s update the examples so that we can fix the argos differences.

[vicasas]

@mnajdova The changes of argos I think are expected. Should the demonstrations in the examples show the primary color or secondary?

For the ColorSwitches demo, green was corrected.

[mnajdova]

Ideally, we shouldn't have changes in argos. We should just do:

-<Switch />
+<Switch color="secondary" />

and

-<Switch color="primary"/>
+<Switch  />

[oliviertassinari]

Ideally, we shouldn't have changes in argos. We should just do:

I'm not so sure, the idea was that "primary" makes more sense. Would we send a contradicting message if the docs don't use it?

[mnajdova]

Thanks!