feat: support creating and calling custom functions with go plugin

examples/plugin/debugtalk.go

@@ -0,0 +1,14 @@
+package main
+
+import (
+	"fmt"
+	"log"
+)
+
+func init() {
+	log.Println("plugin init function called")
+}
+
+func Concatenate(a int, b string, c float64) string {
+	return fmt.Sprintf("%v_%v_%v", a, b, c)
+}