fix(core): improve onTouched handling in core components and add docs

[mikerodonnell89]

fixes #8677

A user of the library recently pointed out that the step input sets onTouched to true too early, and after combing through the library, I found this was the case with many components. According to the Angular documentation, onTouched for a control should be set to true after the control is blurred, not when it is first focused. For us with complex controls that means using focusout as blur only works on the parent element, while focusout works for child elements and bubbles.

[netlify[bot]]

✅ Deploy Preview for fundamental-ngx ready!

Name	Link
🔨 Latest commit	439e56381abee690554bf6e8169aa242d01b4a93
🔍 Latest deploy log	https://app.netlify.com/sites/fundamental-ngx/deploys/633327f99d9caa0008758efd
😎 Deploy Preview	https://deploy-preview-8730--fundamental-ngx.netlify.app/docs/fn/input/examples/input-form-group-example.component
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify site settings.

[github-actions[bot]]

Visit the preview URL for this PR (updated for commit 439e563):

https://fundamental-ngx-gh--pr8730-fix-form-touched-blu-zvj1nin2.web.app

_{(expires Fri, 30 Sep 2022 16:55:48 GMT)}

_{🔥 via Firebase Hosting GitHub Action 🌎}