Add License model

Common `License` class which could be used by all apps to check if user has accepted SLUL

modules/runtime-common/src/main/scala/com/snowplowanalytics/snowplow/runtime/License.scala

@@ -0,0 +1,33 @@
+/*
+ * Copyright (c) 2023-present Snowplow Analytics Ltd. All rights reserved.
+ *
+ * This program is licensed to you under the Snowplow Community License Version 1.0,
+ * and you may not use this file except in compliance with the Snowplow Community License Version 1.0.
+ * You may obtain a copy of the Snowplow Community License Version 1.0 at https://docs.snowplow.io/community-license-1.0
+ */
+package com.snowplowanalytics.snowplow.runtime
+
+import cats.effect.Sync
+import io.circe.Decoder
+
+final case class License(accept: Boolean)
+
+object License {
+
+  def check[F[_]: Sync](value: License): F[Unit] =
+    if (value.accept)
+      Sync[F].unit
+    else
+      Sync[F].raiseError(
+        new IllegalStateException(
+          "Please accept the terms of the Snowplow Limited Use License Agreement to proceed. See https://docs.snowplow.io/docs/pipeline-components-and-applications/stream-collector/configure/#license for more information on the license and how to configure this."
+        )
+      )
+
+  implicit val licenseDecoder: Decoder[License] = {
+    val truthy = Set("true", "yes", "on", "1")
+    Decoder
+      .forProduct1("accept")((s: String) => License(truthy(s.toLowerCase())))
+      .or(Decoder.forProduct1("accept")((b: Boolean) => License(b)))
+  }
+}

modules/runtime-common/src/test/scala/com/snowplowanalytics/snowplow/runtime/LicenseSpec.scala

@@ -0,0 +1,77 @@
+/*
+ * Copyright (c) 2023-present Snowplow Analytics Ltd. All rights reserved.
+ *
+ * This program is licensed to you under the Snowplow Community License Version 1.0,
+ * and you may not use this file except in compliance with the Snowplow Community License Version 1.0.
+ * You may obtain a copy of the Snowplow Community License Version 1.0 at https://docs.snowplow.io/community-license-1.0
+ */
+package com.snowplowanalytics.snowplow.runtime
+
+import cats.effect.IO
+import cats.effect.testing.specs2.CatsEffect
+import io.circe.Decoder
+import io.circe.generic.semiauto.deriveDecoder
+import io.circe.literal.JsonStringContext
+import org.specs2.Specification
+
+class LicenseSpec extends Specification with CatsEffect {
+
+  def is = s2"""
+      Decoding license 'accept' value should be true for:
+        boolean true $e1
+        string "true" $e2
+        string "yes" $e3
+        string "on" $e4
+        string "1" $e5
+      Decoding license 'accept' value should be false for:
+        boolean false $e6
+        string "false" $e7
+        any 'non-truthy' string like "something" $e8
+      Checking license should do nothing if accept flag is true $e9  
+      Checking license should raise error if accept flag is false $e10  
+        """
+
+  def e1 =
+    json"""{"accept": true}""".as[License] must beRight(License(accept = true))
+
+  def e2 =
+    json"""{"accept": "true"}""".as[License] must beRight(License(accept = true))
+
+  def e3 =
+    json"""{"accept": "yes"}""".as[License] must beRight(License(accept = true))
+
+  def e4 =
+    json"""{"accept": "on"}""".as[License] must beRight(License(accept = true))
+
+  def e5 =
+    json"""{"accept": "1"}""".as[License] must beRight(License(accept = true))
+
+  def e6 =
+    json"""{"accept": false}""".as[License] must beRight(License(accept = false))
+
+  def e7 =
+    json"""{"accept": "false"}""".as[License] must beRight(License(accept = false))
+
+  def e8 =
+    json"""{"accept": "something"}""".as[License] must beRight(License(accept = false))
+
+  def e9 =
+    License.check[IO](License(accept = true)).map(result => result must beEqualTo(()))
+
+  def e10 =
+    License
+      .check[IO](License(accept = false))
+      .attempt
+      .map { result =>
+        result must beLeft.like { case ex: Throwable =>
+          ex.getMessage must beEqualTo(
+            "Please accept the terms of the Snowplow Limited Use License Agreement to proceed. See https://docs.snowplow.io/docs/pipeline-components-and-applications/stream-collector/configure/#license for more information on the license and how to configure this."
+          )
+        }
+      }
+}
+
+object LicenseSpec {
+  final case class TestConfig(license: License)
+  implicit val testConfigDecoder: Decoder[TestConfig] = deriveDecoder[TestConfig]
+}