blocks: Add cpuparticles2d_finished

This block is useful to do an action when a one-shot particle emitter is
finished emitting.

Author: dylanmccall

addons/block_code/blocks/spawn/cpuparticles2d_finished.tres

@@ -0,0 +1,17 @@
+[gd_resource type="Resource" load_steps=2 format=3 uid="uid://c188gpgf4rpns"]
+
+[ext_resource type="Script" path="res://addons/block_code/code_generation/block_definition.gd" id="1_pmpup"]
+
+[resource]
+script = ExtResource("1_pmpup")
+name = &"cpuparticles2d_finished"
+target_node_class = "CPUParticles2D"
+description = "Emitted when all active particles have finished processing."
+category = "Lifecycle | Spawn"
+type = 1
+variant_type = 0
+display_template = "when particles are finished"
+code_template = ""
+defaults = {}
+signal_name = "finished"
+scope = ""