Base PGPainlessCLI on new sop-java module

* Rename pgpainless-sop -> pgpainless-cli
* Introduce sop-java (implementation-independent SOP API)
* Introduce sop-java-picocli (CLI frontend for sop-java)
* Introduce pgpainless-sop (implementation of sop-java using PGPainless)
* Rework pgpainless-cli (plugs pgpainless-sop into sop-java-picocli)

sop-java-picocli/src/test/java/sop/cli/picocli/SOPTest.java

@@ -0,0 +1,42 @@
+/*
+ * Copyright 2021 Paul Schaub.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package sop.cli.picocli;
+
+import static org.mockito.Mockito.mock;
+
+import com.ginsberg.junit.exit.ExpectSystemExitWithStatus;
+import org.junit.jupiter.api.Test;
+import sop.SOP;
+
+public class SOPTest {
+
+    @Test
+    @ExpectSystemExitWithStatus(69)
+    public void assertExitOnInvalidSubcommand() {
+        SOP sop = mock(SOP.class);
+        SopCLI.setSopInstance(sop);
+
+        SopCLI.main(new String[] {"invalid"});
+    }
+
+    @Test
+    @ExpectSystemExitWithStatus(1)
+    public void assertThrowsIfNoSOPBackendSet() {
+        SopCLI.SOP_INSTANCE = null;
+        // At this point, no SOP backend is set, so an InvalidStateException triggers exit(1)
+        SopCLI.main(new String[] {"armor"});
+    }
+}