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/src/main/java/sop/Verification.java

@@ -0,0 +1,69 @@
+/*
+ * 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;
+
+import java.util.Date;
+
+import sop.util.UTCUtil;
+
+public class Verification {
+
+    private final Date creationTime;
+    private final String signingKeyFingerprint;
+    private final String signingCertFingerprint;
+
+    public Verification(Date creationTime, String signingKeyFingerprint, String signingCertFingerprint) {
+        this.creationTime = creationTime;
+        this.signingKeyFingerprint = signingKeyFingerprint;
+        this.signingCertFingerprint = signingCertFingerprint;
+    }
+
+    /**
+     * Return the signatures creation time.
+     *
+     * @return signature creation time
+     */
+    public Date getCreationTime() {
+        return creationTime;
+    }
+
+    /**
+     * Return the fingerprint of the signing (sub)key.
+     *
+     * @return signing key fingerprint
+     */
+    public String getSigningKeyFingerprint() {
+        return signingKeyFingerprint;
+    }
+
+    /**
+     * Return the fingerprint fo the signing certificate.
+     *
+     * @return signing certificate fingerprint
+     */
+    public String getSigningCertFingerprint() {
+        return signingCertFingerprint;
+    }
+
+    @Override
+    public String toString() {
+        return UTCUtil.formatUTCDate(getCreationTime()) +
+                ' ' +
+                getSigningKeyFingerprint() +
+                ' ' +
+                getSigningCertFingerprint();
+    }
+}