Add error messages example

[shawnbot]

@nlsfds and I were trying to sort out how different types of validation error messages show up, so I thought I would add an example for it:

https://formio-sfds-git-error-examples.sfds.vercel.app/examples/error-messages

[vercel[bot]]

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🔍 Inspect: https://vercel.com/sfds/formio-sfds/jms10yj5z
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[github-actions[bot]]

Size Change: +6.66 kB (6%) 🔍

Total Size: 98.6 kB

Filename	Size	Change
dist/examples.js	10.7 kB	+7.17 kB (67%)	🆘
dist/examples/example.js	0 B	-508 B (0%)

ℹ️ View Unchanged

| Filename | Size | Change | | |:--- |:---:|:---:|:---:| | `dist/common.css` | 332 B | 0 B | | | `dist/formio-sfds.css` | 14 kB | 0 B | | | `dist/formio-sfds.standalone.js` | 68.2 kB | 0 B | | | `dist/portal.js` | 5.36 kB | 0 B | |

_{compressed-size-action}

[shawnbot]

FYI, this size change doesn't affect the bundle that we use on sf.gov. examples.js is only used on example pages:

Size Change: +6.66 kB (6%) 🔍

Total Size: 98.6 kB

Filename Size Change
dist/examples.js 10.7 kB +7.17 kB (67%) 🆘

[shawnbot]

This isn't "done", but I think it's worth including in the 7.0.3 release. We can always add more error message examples! 🚀