feat: manage map types with additionalProperties

[bdeneux]

This Pull Request introduces improvements to the JSON schema generation process, specifically for Map types. These improvements are in line with the JSON schema draft documentation and the output from the schemars tool.

When a Map is defined, it generates a JSON schema definition where additionalProperties is set to accept the type required by the map value type.

Consider the following Rust code:

#[cw_serde]
#[derive(QueryResponses)]
pub enum QueryMsg {
    /// # MapString
    #[returns(BarResponse)]
    MapString { foo: BTreeMap<String, String> },
    #[returns(BarResponse)]
    MapWithValue { foo: BTreeMap<String, Value> },
}

This code generates the following JSON schemas:

"map_string": {
    "type": "object",
    "required": ["foo"],
    "properties": {
        "foo": {
            "type": "object",
            "additionalProperties": {
                "type": "string"
            }
        }
    },
    "additionalProperties": false
}

"map_with_value": {
    "type": "object",
    "required": ["foo"],
    "properties": {
        "foo": {
            "type": "object",
            "additionalProperties": {
                "$ref": "#/definitions/Value"
            }
        }
    },
    "additionalProperties": false
}

In Go, this should generate a foo property of type map[string]string for the first schema and map[string]Value for the second one.

type QueryMsg_MapString struct {
	Foo map[string]string `json:"foo"`
}

type QueryMsg_MapWithValue struct {
	Foo map[string]Value `json:"foo"`
}

This PR includes modifications to the handling of the additionalProperties field, allowing it to accept either a boolean or a JSONSchema, in line with the JSON schema specification.

Furthermore, when additionalProperties is set to true (which is the default value in JSON Schema), it implies that the object can accept any property with any value. While this does not adhere strictly to the JSON schema specification (because we can set both properties and addionalProperties), it provides a more flexible approach to handling additionalProperties.

[bdeneux]

The schema in question can be found at: https://github.com/axone-protocol/axone-contract-schema/blob/refactor/go-codegen/schema/axone-cognitarium.json.

Please note that this schema has not been added to the test data due to the presence of another issue that is unrelated to additionalProperties but affects the generation process. A separate issue will be created to track and resolve this secondary problem. 🙂

[srdtrk]

Thank you so much for the contribution once again. Looks pretty good, I've left some comments, let's address them and get this merged.

[srdtrk]

Lgtm, left one suggestion, will merge once that's resolved.