Support all String `format` keys

[mwildehahn]

• date-time, eg: 2018-11-13T20:20:39+00:00
• time, eg: 20:20:39+00:00
• email, eg: RFC 5322, section 3.4.1
• idn-email" RFC 6531
• hostname RFC 1034, section 3.1
• idn-hostname RFC5890, section 2.3.2.3
• ipv4 RFC 2673, section 3.2
• ipv6 RFC 2373, section 2.2
• uri RFC3986
• uri-reference RFC3986, section 4.1
• iri RFC3987
• iri-reference RFC3987
• uri-template RFC6570
• json-pointer RFC6901
• "relative-json-pointer https://tools.ietf.org/html/draft-handrews-relative-json-pointer-01
• regex ECMA 262