Fix schema for IpAddr type

[Soneji]

The IpAddr type returns

"format": "ip"

which isn't a valid JSON format type. See here for the correct implementation.

I have changed this type to instead use

"anyOf": [
  {
    "type": "string",
    "format": "ipv4"
  },
  {
    "type": "string",
    "format": "ipv6"
  }
]

[ahl]

I'd suggest this not merge. From the JSON Schema draft 7 spec:

https://json-schema.org/draft-07/draft-handrews-json-schema-validation-01#rfc.section.7.2

Implementations MAY add custom format attributes. Save for agreement between parties, schema authors SHALL NOT expect a peer implementation to support this keyword and/or custom format attributes.

Is there a reason the "ip" format is causing issues for the author? We've found "ip" to be useful.

[ahl]

Could this be a oneOf?

Suggested change

	any_of: Some(vec![
	gen.subschema_for::<Ipv4Addr>(),
	gen.subschema_for::<Ipv6Addr>(),
	]),
	one_of: Some(vec![
	gen.subschema_for::<Ipv4Addr>(),
	gen.subschema_for::<Ipv6Addr>(),
	]),

[ahl]

You might consider this to label the subschemas; this makes it easier for code generators to infer what's going on.

Suggested change

	let schema_object = SchemaObject {
	instance_type: Some(SingleOrVec::Single(Box::new(InstanceType::String))),
	subschemas: Some(Box::new(SubschemaValidation {
	any_of: Some(vec![
	gen.subschema_for::<Ipv4Addr>(),
	gen.subschema_for::<Ipv6Addr>(),
	]),
	..Default::default()
	})),
	..Default::default()
	};
	let schema_object = SchemaObject {
	instance_type: Some(SingleOrVec::Single(Box::new(InstanceType::String))),
	subschemas: Some(Box::new(SubschemaValidation {
	any_of: Some(vec![
	SchemaObject {
	metadata: Some(Box::new(Metadata {
	title: Some("V4".into()),
	..Default::default()
	})),
	subschemas: Some(Box::new(SubschemaValidation {
	all_of: Some(vec![gen.subschema_for::<Ipv4Addr>()]),
	..Default::default()
	})),
	..Default::default()
	}
	.into(),
	SchemaObject {
	metadata: Some(Box::new(Metadata {
	title: Some("V6".into()),
	..Default::default()
	})),
	subschemas: Some(Box::new(SubschemaValidation {
	all_of: Some(vec![gen.subschema_for::<Ipv6Addr>()]),
	..Default::default()
	})),
	..Default::default()
	}
	.into(),
	]),
	..Default::default()
	})),
	..Default::default()
	};