Groundwork for integrating Specta (#949)

* add derive(specta::Type)

* use specta from git

* introduce Uuid type

* remove unnecessary specta::Type

* document export_types test

* upgrade Specta
The previous Specta branch had some hacks that were just for this project. They have all been converted into proper features so they can be merged into main.

* remove some unnecessary specta::Type uses

* add MessageDiscriminantDef explanation

* manually export types with specta

* rename 'specta.rs' to 'export_types.rs'

* rename 'export_types' to 'generate_ts_types'

---------

Co-authored-by: Oscar Beaumont <oscar@otbeaumont.me>

node-graph/gcore/src/uuid.rs

@@ -0,0 +1,42 @@
+use serde::{Deserialize, Serialize};
+
+#[derive(Clone, Copy, Serialize, Deserialize, specta::Type)]
+pub struct Uuid(
+	#[serde(with = "u64_string")]
+	#[specta(type = String)]
+	u64,
+);
+
+mod u64_string {
+	use serde::{self, Deserialize, Deserializer, Serializer};
+	use std::str::FromStr;
+
+	// The signature of a serialize_with function must follow the pattern:
+	//
+	//    fn serialize<S>(&T, S) -> Result<S::Ok, S::Error>
+	//    where
+	//        S: Serializer
+	//
+	// although it may also be generic over the input types T.
+	pub fn serialize<S>(value: &u64, serializer: S) -> Result<S::Ok, S::Error>
+	where
+		S: Serializer,
+	{
+		serializer.serialize_str(&value.to_string())
+	}
+
+	// The signature of a deserialize_with function must follow the pattern:
+	//
+	//    fn deserialize<'de, D>(D) -> Result<T, D::Error>
+	//    where
+	//        D: Deserializer<'de>
+	//
+	// although it may also be generic over the output types T.
+	pub fn deserialize<'de, D>(deserializer: D) -> Result<u64, D::Error>
+	where
+		D: Deserializer<'de>,
+	{
+		let s = String::deserialize(deserializer)?;
+		u64::from_str(&s).map_err(serde::de::Error::custom)
+	}
+}