test/templates: add loading test templates

The loading_test had been added to the repository at first, but were not
versioned at that time, making those tests impossible to run on CI.

test/templates/pin_1.0.9.pkr.hcl

@@ -0,0 +1,14 @@
+packer {
+	required_plugins {
+		tester = {
+			source = "github.com/hashicorp/tester"
+			version = "= 1.0.9"
+		}
+	}
+}
+
+source "tester-dynamic" "test" {}
+
+build {
+	sources = ["tester-dynamic.test"]
+}

test/templates/simple.json

@@ -0,0 +1,6 @@
+{
+	"builders": [{
+		"type": "tester-dynamic",
+		"name": "test"
+	}]
+}