Sanitize Person name when creating an account

### Description

Need to sanitize the `Person` name fields (and similar fields) when creating a new account and at any other places where someone might try to be abusive.

These should not accept HTML.

### Code of Conduct

- [X] I agree to follow the [IETF's Code of Conduct](https://github.com/ietf-tools/.github/blob/main/CODE_OF_CONDUCT.md)