Implement begining of migration

Move Function/Query definition

src/main/kotlin/fr/postgresjson/definition/Parameter.kt

@@ -0,0 +1,34 @@
+package fr.postgresjson.definition
+
+interface ParameterI {
+    val name: String
+    val type: String
+    val direction: Parameter.Direction
+    val default: String
+}
+
+class Parameter(val name: String, val type: String, direction: Direction? = Direction.IN, val default: Any? = null)
+{
+    val direction: Direction
+
+    init {
+        if (direction === null) {
+            this.direction = Direction.IN
+        } else {
+            this.direction = direction
+        }
+    }
+
+    constructor(name: String, type: String, direction: String? = "IN", default: Any? = null) : this(
+        name = name,
+        type = type,
+        direction = direction?.let { Direction.valueOf(direction.toUpperCase())},
+        default = default
+    )
+
+    enum class Direction { IN, OUT, INOUT }
+}
+
+interface ParametersInterface {
+    val parameters: List<Parameter>
+}