Refactor for bindgen updates

[bhelx]

See dylibso/xtp-bindgen#18

Required Vs Nullable

Picking up where #10 left off . How i am implementing required vs nullable

This schema:

    RequiredVsNullable:
      description: A weird little object
      required:
        - aRequiredNotNullableBoolean
        - aRequiredNullableBoolean
      properties:
        aRequiredNotNullableBoolean:
          type: boolean
          description: A required, not-nullable boolean prop
        aRequiredNullableBoolean:
          type: boolean
          description: A required ,nullable boolean prop
          nullable: true
        aNotRequiredNotNullableBoolean:
          type: boolean
          description: A not-required, not-nullable boolean prop
        aNotRequiredNullableBoolean:
          type: boolean
          description: A not-required, nullable boolean prop
          nullable: true

Results in this object:

    #[derive(
        Default, serde::Serialize, serde::Deserialize, extism_pdk::FromBytes, extism_pdk::ToBytes,
    )]
    #[encoding(Json)]
    pub struct RequiredVsNullable {
        /// A not-nullable boolean prop
        #[serde(rename = "aNotRequiredNotNullableBoolean")]
        #[serde(skip_serializing_if = "Option::is_none")]
        #[serde(default = "panic_if_key_missing")]
        pub a_not_required_not_nullable_boolean: Option<bool>,

        /// A nullable boolean prop
        #[serde(rename = "aNotRequiredNullableBoolean")]
        #[serde(skip_serializing_if = "Option::is_none")]
        #[serde(default = "panic_if_key_missing")]
        pub a_not_required_nullable_boolean: Option<bool>,

        /// A not-nullable boolean prop
        #[serde(rename = "aRequiredNotNullableBoolean")]
        pub a_required_not_nullable_boolean: bool,

        /// A nullable boolean prop
        #[serde(rename = "aRequiredNullableBoolean")]
        #[serde(default)]
        pub a_required_nullable_boolean: Option<bool>,
    }

[bhelx]

note: we have a type for i64 but don't yet support it because of json limitations. i have an issue filed for this.

[chrisdickinson]

We might want to use serde_json::Value::Map instead of HashMap while we're here. (serde_json::Map gives the plugin author the ability to preserve key order.)

[zshipko]

Closing since this work was included in #18