Add Odin submodule and syntax test file

tests/syntax-tests/highlighted/Odin/test.odin

@@ -0,0 +1,27 @@
+package main
+
+import "core:fmt"
+import "core:math"
+
+Vector :: struct {
+	components: []f64,
+}
+
+euclidean_distance :: proc(v1: Vector, v2: Vector) -> f64 {
+	if len(v1.components) != len(v2.components) {
+		panic("Vectors must be same dimension")
+	}
+	sum: f64 = 0.0;
+	for i, comp in v1.components {
+		diff := comp - v2.components[i];
+		sum += diff * diff;
+	}
+	return math.sqrt(sum);
+}
+
+main :: proc() {
+	v1: Vector = Vector{components = []f64{1.0, 2.0, 3.0}};
+	v2: Vector = Vector{components = []f64{4.0, 6.0, 8.0}};
+	dist: f64 = euclidean_distance(v1, v2);
+	fmt.println("Distance:", dist);
+}