Development Validation Plugin

[harlan-zw]

Describe the feature

We should make a plugin that validates the final head output that the user provided and warn them about common issues.

Some examples:

• using unknown meta tags (would catch incorrect usage of property / name for og tags)
• using unknown props (we allow them to fallthrough atm)
• non-absolute canonical
• non-absolute og images
• incorrectly formatted twitter handle Automatic add of @ for twitter site on useSeoMeta #309
• Add warning when there is double/conflict of head tags #385

This would only run in development.

Additional information

• Would you be willing to help implement this feature?